Ordinary Plain Meaning: Defining Terms in a Patent Application

By Gene Quinn
January 23, 2012

We say all the time that in a patent application you can define the terms you want to use in the claims to give them the meaning you intend; the meaning that will apply during any claim interpretation.  But what happens when you do not define a term in the specification?  Well, that really all depends.  As a general rule the ordinary plan meaning of the term will be used.  This issue of defined meaning arose recently in a high profile case, giving us a chance to review the ruling and discuss defining terms more generally.

Recently in the ongoing patent war between Apple and Motorola, Judge Richard Posner of the United States Court of Appeals for the Seventh Circuit issued a ruling, while sitting by designation as a trial judge.  See Apple v. Motorola No. 1:11-cv-08540 (N.D. IL., Jan. 17, 2012). Motorola had argued that Apple’s U.S. Patent No. 7,479,949 was invalid because it used the term “heuristic,” thereby rendering the claims invalid as being indefinite and in violation of 35 U.S.C. 112, ¶ 2.

Motorola’s primary evidence of indefiniteness consisted of statements in various depositions taken during discover.  The nine listed inventors were deposed and most of them conceded that the term “heuristics” is “sort of a vague word.”  They were also unable to suggest an appropriate definition.  Nevertheless, Judge Posner agreed that the definition of heuristics provided by Apple for purpose of claim construction was appropriate and keeping with the patent disclosure.  Apple defined “heuristics” to mean “one or more rules to be applied to data to assist in drawing inferences from the data.”

Judge Posner, citing Solomon v. Kimberly-Clark Corp., 216 Fe.3d 1372, 1379 (Fed. Cir. 2000), explained that it is inappropriate to consider inventor testimony when assessing validity under section 112, ¶ 2.  For the uninitiated that may seem odd, but it really has to be that way. The question isn’t whether inventors or even someone of skill in the art can define any particular term, but rather whether the invention is particularly defined and whether someone of skill in the art would understand the invention and be able to both make and use the invention.  In essence, the inquiry is one of a totality of circumstances.


The question of whether a term is defined adequately is really a legal question, so the views and opinions of those who are not well versed in the law are hardly probative.  Inventors invent and patent attorneys describe those inventions to satisfy the legal requirements.  If inventors could describe their inventions to meet the legal requirements they wouldn’t need patent attorneys, but we all know that inventors who represent themselves make numerous errors and always obtain far more narrow protection than they would have been entitled to receive.  They just don’t understand the law well enough and are not qualified to offer opinions on matters of law.

Generally speaking, the Manual of Patent Examining Procedures explains that an applicant is entitled to be his or her own lexicographer, giving their ordinary and customary meaning by clearly setting forth a definition of the term.  This can allow the applicant to even give meanings to terms that are somewhat different from the ordinary and customary meaning(s), although you can’t define terms so that they are diametrically opposite to their ordinary meaning.  See e.g. MPEP 2111.01.  So you couldn’t say “when I say ‘up’ I mean ‘down’ and when I say ‘down’ I mean ‘up’.”  This up/down example is a favorite example of John White when he lectures in the PLI Patent Bar Review Course.

One of the seminal cases dealing with defining terms in a patent application is the Federal Circuit’s decision in Phillips v. AWH Corporation.  Beginning with the Phillips ruling the Federal Circuit ushered in a new era of clarity in so far as interpreting patent claims is concerned.  Remarkable is the fact that the Federal Circuit was able to do so without any monumental sifts in the fundamental core principles of patent law.  In fact, the decision discussed at length tried and true principles of claim construction, and seems to have even been able to come up with an end result that makes sense and can be applied evenly by district courts.

It is not overstating the matter to say that to both Phillips and AWH Corporation the entire case rested upon the meaning of the term “baffle.”  For the rest of us the thing that made this case noteworthy was the hope that the entire court sitting as one might be able to make some sense out of the hopelessly conflicting precedent surrounding the appropriate use of the specification, dictionaries and treatises when engaging in the hardly scientific analysis of construing claims.

As a result of what can only be characterized as confusing and conflicting precedent relating to the appropriate use of extrinsic evidence, the entire Federal Circuit decided to rehear Phillips v. AWH Corporation case en banc in order to resolve issues concerning the construction of patent claims.  In what turned out to be a rather lengthy decision the Federal Circuit, apparently to make sure that the confusing nature of the law was properly clarified, explained the fundamental principles associated with interpreting patent claims, from the very beginning.  Those looking for a primer on the issue should really read the entire decision.

To some extent, the experience of reading the decision was akin to asking someone “how was your day” and the answer beginning with “I woke up at 5:30am and then showered and brushed my teeth …”  In defense of the Federal Circuit, however, certain lines of cases had so confused what should have been easy to understand, well-established law that starting at the beginning was not a half-bad idea.  Then, just as this page turner got to the point where it was starting to get good it ended in a quick, sensible decision.  Good for patent law, bad for commentators.

Rather than dance around the issue of erroneous previous decision as so many courts so often do, the Federal Circuit acknowledged that some of its previous decisions have suggested an approach to claim construction whereby greater emphasis was given to dictionary definitions of claim terms and a less prominent role given to the specification and the prosecution history. The Federal Circuit then identified Texas Digital Systems, Inc. v. Telegnix (2002) as the leading case in this now defunct line and summarily executed it in an Terminator kind of way, minus of course any of the excitement.

The Texas Digital Systems court had determined that it was improper to consult the written description and prosecution history as a threshold step in the claim construction process, before any effort is made to discern the ordinary and customary meanings attributed to the words themselves.  The fact that this so clearly deviated from accepted reasoning didn’t seem to matter at the time, but sanity once again prevailed.  After all, if the patentee is to be his or her own lexicographer and that the patent is to be written for those skilled in the art, shouldn’t we first read the entire patent file, including the claims, specification and the prosecution history?


The Federal Circuit was not, however, ready to completely throw the Texas Digital court under the bus.  The Phillips decision went to lengths to empathize with what the Texas Digital court was trying to do, which was prevent the importation of limitations from the specification into the claims.  Notwithstanding this olive branch, the Phillips decision clearly explains that the methodology adopted by the Texas Digital court simply placed too much reliance on extrinsic sources such as dictionaries, treatises, and encyclopedias and too little on intrinsic sources, in particular the  specification and prosecution history.

After dismissing the Texas Digital line of cases the Federal Circuit congratulated the decision in Vitronics Corp. v. Conceptronic, Inc. (1996) as striking the appropriate methodology for claim construction.  The Federal Circuit recognized in Vitronics, there is no magic formula for conducting claim construction. A district court is not barred from considering any particular sources or required to analyze sources in any specific sequence, as long as those sources are not used to contradict claim meaning that is unambiguous in light of the intrinsic evidence. The sequence of steps used by the judge in consulting various sources is not important; what matters is for the court to attach the appropriate weight to be assigned to those sources in light of the statutes and policies that inform patent law.

As a result of the Phillips case and more recent decisions, dictionaries and treatises will still be able to be used in interpreting claims, but intrinsic evidence, namely the claims, the specification and the prosecution history, are of primary importance.  The focus must always be on what one skilled in the art would understand, which is certainly in line with other patent law requirements, particularly the requirements set forth in 35 U.S.C. 112.

Notwithstanding, the focus on one of skill in the art does not mean that inventors or those skilled in the art are thrown into the deep end as they struggle to understand the meaning of the terms used.  Claim construction is a question of law that requires careful understanding of the many nuanced legal rules.  The fact that one of skill in the art, or even the inventor, cannot articulate the meaning of a term used by a patent attorney in context does not render a claim invalid.

The Author

Gene Quinn

Gene Quinn is a Patent Attorney and Editor and President & CEO ofIPWatchdog, Inc.. Gene founded IPWatchdog.com in 1999. Gene is also a principal lecturer in the PLI Patent Bar Review Course and Of Counsel to the law firm of Berenato & White, LLC. Gene’s specialty is in the area of strategic patent consulting, patent application drafting and patent prosecution. He consults with attorneys facing peculiar procedural issues at the Patent Office, advises investors and executives on patent law changes and pending litigation matters, and works with start-up businesses throughout the United States and around the world, primarily dealing with software and computer related innovations. is admitted to practice law in New Hampshire, is a Registered Patent Attorney and is also admitted to practice before the United States Court of Appeals for the Federal Circuit. CLICK HERE to send Gene a message.

Warning & Disclaimer: The pages, articles and comments on IPWatchdog.com do not constitute legal advice, nor do they create any attorney-client relationship. The articles published express the personal opinion and views of the author as of the time of publication and should not be attributed to the author’s employer, clients or the sponsors of IPWatchdog.com. Read more.

Discuss this

There are currently 25 Comments comments.

  1. step back January 24, 2012 6:35 am


    A couple of typos “up” above.
    “assit” should be –assist–
    “favor” should be –favorite–

    Spell check does not trump a read through by a human being
    (Then again, this is the internet and I might be a dog 🙂 /” )

  2. EG January 24, 2012 7:48 am


    I now ALWAYS provide a Definition section in each application I prepare, be it provisional or non-provisional. Every key claim term is defined, as well as those terms which might appear in the claim later. This has been fundamental practice for me for at least the last 7 years and is essentially equivalent to what you do in a contract. Put it this way, I would rather define the playing field that governs the claim terms in the application, rather than allowing my opponent to do so (e.g., in litigation) because I neglected to exercise the applicant’s legal right to do so. Defining claim terms in the application also helps when you explain to the patent examiner why their view that a defined claim term is “indefinite” (because they FAILED to consider your definition of that term in the specification) won’t wash.

  3. tifoso January 24, 2012 8:06 am

    Gene –

    The inquiry into extracting meaning from words has bedeviled linguists and lawyers for centuries. We easily slide into using such terms as *the* ordinary meaning of a word when, upon thorough examination, we must accept that few words have only one meaning. Context controls meaning. The champion word in English is “run” which has some 180 meanings according to my Unabridged Webster’s Dictionary. We comprehend the meaning when we comprehend the context. Does the word refer to a means of locomotion, a stream, a defect in knitted fabric, what? Thus, failure to read the Specification to dig out meaning is a fool’s errand which will often lead to grief. Without context, there seldom can be meaning.

    So, do we rely on dictionaries? Dictionaries are often misunderstood. To use the Aristolean analogy of the mirror and the lamp, far too many people believe that dictionaries tell us the “right” meaning of a word, that is, they are lamps that light the way to The Truth. The Truth is that dictionaries are merely compiled reports of usages. They are mirrors that reflect meaning in a democratic way. If a plurality uses a word in a given way, that is its meaning. The same goes for pronunciation.

    Words change meaning with time. We get confusion between “parameter” and “perimeter” to the point that the first has taken on the meaning of the second. Witness the use of “forthcoming” to mean “forthright” rather than “in the future”. With time, we come to accept the new meanings, Mrs. Malaprop notwithstanding. Nouns become verbs, e.g., “impact”.

    Contrary to the example from one of the cases cited, words often swap meanings or assume their opposite. Consider the use of “bad” to mean “good”, a meaning heavily used by the late Michael Jackson. Slang becomes ordinary speech.

    Some words carry contrary meanings. Is a giraffe “peculiar” to the North Pole? When I send an envelope with a letter inside, which is the “enclosure”? If it is that which is contained, how about a sheep pen as an “enclosure”, that is, that which encloses? Examples abound.

    For the record, so readers do not assume I am a foreigner, a Ferenghi, here to make trouble, my undergrad degree was in English Literature and Master’s in Computer Science where I concentrated on a sub-topic of Artificial Intelligence known as Natural Language Language. I co-authored the 1977 Fortran Language Standard in a formal metalanguage (BNF) in hopes of avoiding the ambiguities that arise with natural language. All these years of study have taught me that, like Sergeant Schultz, I know nothing. I easily can come up with more and more interesting questions which I cannot answer. In addition, I have a law degree and am admitted before the PTO. Any trouble I make is intramural.

    And so to work.


  4. American Cowboy January 24, 2012 11:06 am

    EG and Tifoso, thanks for enlightening posts.

    EG, could you post the numbers of a couple of your published applications or patents that you consider to be exemplary of your style of providing definitions of terms?

  5. Gene Quinn January 24, 2012 11:40 am


    Thanks. Fixed those typos. I am a terrible proof reader of my own writings. I’ll blame it on my inner electrical engineer.



  6. Gene Quinn January 24, 2012 11:44 am


    Excellent comment. Do you have any interest in turning that comment into an article for publication?


    I’d like to see some examples of your definition sections as well.



  7. Stan E. Delo January 24, 2012 4:49 pm


    I would be very interested as well, as I had to sorta invent some new terminolgy while figuring out what might be the best way to express the concepts involved as accurately as possible. My practitioner happened to grasp the principles very quickly, but one of the first things we had to do was define what is meant by *increasing or decreasing* the pitch of a propeller blade, for just one instance. My take on it was that as long as the terminology was consistent throughout the application, most folks should be able to figure out what we are trying to say. He seemed to agree, and we then took it from there.

    Thanks for the great post Tifoso-

  8. tifoso January 24, 2012 5:00 pm

    Stan and others –

    Thank you for the compliments. Gene has asked me to expand the above into an article. There is so very much more on that topic. I will do that when I find my desk under all the paper.

    Maybe by bouncing this around, we can come up with a way of solving the problem. Should there be a Glossary Section (if not by that name but by usage) in the Specification? What should it look like? Another case of far more questions than answers.

    And so to work.


  9. EG January 24, 2012 5:18 pm

    AC and Stan,

    Here are three issued patents you can look at that illustrate my Definition sections: US7551336, US767844, and US8009277. Collectively, they illustrate this technique for a minature actuator scanner for multiplexing holographic data, thermoformed articles comprising renewable polymer layers, and a sensor technique for black liquor oxidation control. In other words, this technique isn’t limited to particular technologies. Hope that’s helpful.

    Like you, Stan, I not infrequently have to create new terms because those that exist won’t do enough. Again, part of being the “lexicographer” for the applicant.

  10. Stan E. Delo January 24, 2012 5:21 pm

    I am reminded of the description of the drawings or figures section currently used in most patent applications. What to call it is a very good question indeed. Per EG’s suggestion, perhaps contract law might suggest a few things? I believe property law is a States issue, unless you try to acquire a patent right, it would seem.


  11. Stan E. Delo January 24, 2012 6:28 pm

    I like this idea rather a lot. A whole section Just dedicated to defining what particular words might mean as regards the extant invention being presented. Context. Off to look at your 336 patent, after having glanced at your 277 patent.


  12. step back January 25, 2012 5:49 am


    Be wary of absolutist solutions.
    A mini-dictionary within your spec can be a double edged sword and cut against you as well as it might cut in your favor.
    Often an inventor will not truly fully understand his own invention while standing too close to the birth blood of his creation. It may be many years later before you see how to better define it. But by the it might be too late, because you wrote a wrist-slitting mini-dictionary and stuck it unretractably into your spec.

  13. step back January 25, 2012 5:50 am

    But by “then” …

  14. EG January 25, 2012 9:09 am

    Step Back,

    I will agree that providing a Definition section in an application is not a “silver bullet,” and that the definitions provided cannot be done carelessly but require thought and effort (just like claim drafting). But the alternative of providing no deffinitions for key claim terms is, in my opinion, even worse. First, I’ve reviewed many, many Federal Circuit cases involving claim construction. What usually becomes the problem is not that a key claim is defined in the specification, but is, instead, left undefined and/or unclear. That leaves everyone, including the Federal Circuit, guessing what the intended meaning of the claim terms should be.

    Second, ever since the Federal Circuit’s en banc ruling in Phillips v. AWH Corp., reliance upon extrinsic evidence (e.g., dictionaries) for construing claim terms is, in my opinion, dangerous. After Phillips, intrinsic evidence (e.g., that which is in the patent application such as defining claim terms) has clear priority over extrinsic evidence. In fact, the Federal Circuit now generally frowns upon dictionaries unless it can’t resolve claim construction without them (and generally favors using a particular dictionary, 3rd Webster’s International which may not be to the advantage of the patent applicant).

    Third, the default for construing a claim terms is, as Gene stated, the “ordinary and plain meaning.” That leads to this question: what source do you use to determine the “ordinary and plain meaning” of that term? A scientific dictionary or 3rd Webster’s International? Which scientific dictionary and how do you resolve conflicting or divergent definitions? Frankly, I see much more danger in not defining the claim term in the application than leaving it to chance as to what a patent examiner, judge, jury, etc., will later determine what the “ordinary and plain meaning” of that term is. And I again come back to my main point in including a Definitions section: dictating the playing field for the applicaition, rather than letting my opponent do so.

    You also say “Often an inventor will not truly fully understand his own invention.” That may be true, but that sounds like a “written description” or “enablement” issue, not a claim construction issue. Once upon a time, putting in broad scope claim terms that were undefined in the application might work. But the fact is that the Federal Circuit (and even the USPTO) is now clamping down on such “nebulous” claim terms that are undefined and being urged by the patentee to be given broad scope, even when that scope isn’t “enabled” by what’s described in application. The “brave new patent world” of today is you get what “enable” and particularly what you “define” as your own lexicographer which the law clearly permits you to do.

  15. EG January 25, 2012 9:28 am

    To all:

    Sorry, the second patent listed should be US7678444 (I left off the last “4”).

  16. tifoso January 25, 2012 10:00 am

    EG –

    Agree wholeheartedly. By providing a Glossary (there is a reason why we should use that instead of Definitions but that is an issue for later), we are providing what are our axioms upon which the system is built (to borrow from Euclid, et al.).

    You correctly cite the risk of letting someone else define your terms. While not a patent case, there was a case in California involving Data General, a computer vendor operating around 1980. As best I can recall it was a combined tort-contracts case. One of the complaints against the company was that something the company had done had “locked in” the user. (Now, Microsoft would never do such a thing, would it? GGG.) The term “locked in” we know to be a metaphor meaning that the user’s future choices were either limited or eliminated entirely. Much of our language is metaphorical and therein lies the rub. When the case went to the jury, the jury came back and asked to see “the lock”. Throughout the trial, jurors assumed what was at issue was a physical lock. I do not recall the verdict but plaintiff’s counsel had clearly erred in not defining terms.

    Good comments, EG.


  17. EG January 25, 2012 10:12 am

    To all:

    One other patent to consider for this Definitions section technique is US7336409 (a miniature flexure scanner). Creating the drawings for this flexure scanner was also an interesting exercise, to say the least.

  18. EG January 25, 2012 10:14 am


    Thanks for the further comments. Very interesting, amusing, and sadly, illustrative story of how terms (and jargon) we use may have multiple meanings depending upon the audience.

  19. American Cowboy January 25, 2012 12:19 pm

    A thought occurred to me. If you spell out the definitions in the spec and for one reason or another (late-discovered prior art being a likely candidate) you want to tweak the definition during prosecution.

    Is that do-able?
    Do you raise new matter, written description or enablement issues if you amend the definition?

  20. tifoso January 25, 2012 12:30 pm

    AC –

    The Glossary is a part of the specification. Thus, it cannot be changed except for corrections of form. Hard to imagine a set of facts that would apply. How would prior art lead to necessity to change a definition? Can prior art lead to necessity change any other part of a specification once filed?


  21. tifoso January 25, 2012 12:31 pm

    “necessity to change”

  22. Stan E. Delo January 25, 2012 2:28 pm

    Might it be possible to add a new claim that is meant to alter or clarify the definition of a term that is used in the specification? The spec wouldn’t have to be changed, so no problem there it would seem, but I am not sure if an approach like that would be possible, since I am not formally trained. I am imagining that it would only work during prosecution to get an allowance, and would not be possible to be used to avoid third parties from invalidating a granted patent right?

    It would seem to avoid the possible problems that Step mentioned in #12 once the application gets a little further down the road, and the invention is a little more clearly understood. Right as rain Step Back, as regards the inventor fully comprehending what the invention actually amounts to. After I built a working proto of my current project, a seemingly fairly simple mechanism was doing things that were a bit complex to even try to understand, let alone figuring out what it was doing and why.


  23. American Cowboy January 25, 2012 2:38 pm

    Well, to use an one of EG’s definitions as an example, in US7678444, he used this definition:
    “For the purposes of the present invention, the term “heat-resistant polymer” refers to a polymer (or polymers) which has an HDI value of greater than about 50.degree. C., for example greater than about 65.degree. C. (e.g., greater than about 90.degree. C.). In other words, heat-resistant polymers are resistant to deformation at temperatures above about 50.degree. C., for example, above about 65.degree. C. (e.g., above about 90.degree. C.). Heat-resistant polymers may or may not renewable polymers and may include polyolefins (e.g., polyethylene, polypropylene, etc.), polystyrenes, polyesters, polyamides, polyimides, polyurethanes, cellulose-based polymers, such as cellulose propionate, etc., and combinations thereof. ”

    Suppose the examiner finds reference A that teaches the use of polyurethanes but none of the other named polymers in a way that the examiner says supports an obviousness rejection of a claim that includes as an element a “heat-resistant polymer.” The applicant can point to reference B that says in similar circumstances polyurethane has heat resistant properties but the other named polymers don’t. Can the applicant amend the definition to exclude polyurethane and then say that the the examiner’s reference taken in light of the teaching of reference B does not make the claimed invention obvious? Should the applicant not amend the spec but add a negative limitation to the claim to say a “heat-resistant polymer that is not polyurethane?”

    How does he argue for patentablity of the reduced genus once you take out polyurethane, however that is done?

    By the way, I am NOT a polymer chemist, so I have no idea if what I hypothesized is gibberish technically or not, but hopefully I have highlighted the situation.

  24. EG January 25, 2012 4:10 pm

    “How does he argue for patentablity of the reduced genus once you take out polyurethane, however that is done?”


    The beauty of defining the term “heat-resistant polymer” as I’ve done is that you can make it as broad (or as narow) as is needed for the claims. In your example, since “polyurethane” is an exemplified (but not the only)heat-resistant polymer,” if the reference teaches only “polyurethane” you could then amend the claim to say “heat-resistant polymers other than polyurethanes” (that’s permitted by specific CCPA or Federal Circuit case law.

    “How does he argue for patentablity of the reduced genus once you take out polyurethane, however that is done/”


    Another beauty of creating you own definition (e.g., “heat-resistant polymer”) is that you’ve created this new genus of polymers, not the art. Accordingly, while the reference may teach “polyurethane,” that reference will likely not teach the critical feature (“heat-resistant”) that ties the polymers together in that created genus, only (by chance) one species of that created genus. Unless the reference shows the relationship of the created genus (“heat-resistant polymers”), there is no basis for rejecting the reduced genus of “heat-resistant polymers.” Not infrequently, patent examiners will try to argue those polymers are related but it’s because they’re impermissibly “peeking” at your application specification as the “road map” to that relationship. The case law is also clear that that is a “no, no.”

  25. EG January 25, 2012 4:23 pm


    Another reason for creating your own definition for claim terms is that some patent examiners may get lazy and simply base their search (and rejections) on what references come up based on the selected word criteria (by simply looking at the terms in your claims instead ofreading your application spec to determine what those terms really mean, in context), rather than looking at the context of how those words appear in the cited references. When you create a new term (e.g., a new polymer genus), you may frustrate the patent examiner from doing such rejections based simply on what the word search criteria provide, and instead force them to consider the context of how the claim terms appear in each reference (important when you’re talking about rejections under 35 USC 103 where references are combined).