Patent Drafting: The Use of Relative Terminology Can Be Dangerous

By Gene Quinn
January 30, 2016

jargonThe use of relative terminology, which are short-hand terms that express a certain similarity, are quite common in every day conversation, but are not always appropriate for patent applications, or more specifically for patent claims. This is true because patent claims must particularly pointing out and distinctly claiming the subject matter invented. See Distinctly identifying the invention in exact terms. Therefore, the use of relative terminology in patent claims should be carefully considered. Traps do await the unwary.

Relative terminology can be dangerous because some words are you might want to use are not terribly descriptive, or at least not nearly as descriptive as you might otherwise think. The relational description you are providing by incorporating relative terminology can easily leave open the possibility of miscommunication and ambiguity. Ambiguity is the archenemy of patent drafters and must be avoided at all costs.

Terms such as “like”, “similar”, “type” and others will simply not convey a positive description. These and other similar terms will instead only provide a relational description. When using this type of relative terminology you are not describing the action, item, or element itself directly, but rather you are describing in terms of what it has in common with something else. In many situations this other thing you are drawing a comparison with is not relevant to the invention, which will itself create potential confusion.

On the other hand, terms like “approximately” and “substantially” do provide more information and generally do clearly convey a meaningful relationship. With respect to relative terminology such as “approximately” or “substantially,” the question will be what is “approximately” or what is “substantially”?

The use of relative terminology in patent claim language will not automatically render the claim indefinite under 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112, second paragraph. See Seattle Box Co., Inc. v. Industrial Crating & Packing, Inc., 731 F.2d 818, 221 USPQ 568 (Fed. Cir. 1984). The acceptability of the claim language depends on whether one of ordinary skill in the art most closely pertaining to the invention would understand what is claimed in light of the specification.


In essence, if you are going to use relative terminology in your patent claims the question is whether one of ordinary skill would understand what you mean with enough certainty so as to satisfy the requirement that the patent claim particularly point out and distinctly claim the subject matter invented.

In order for relative terminology to be appropriate in the patent claims the disclosure needs to provide guidance. Sometimes that guidance can be provided simply by the technology context. For example, if you go to the Pet Store and you want to buy a tank of fresh water fish you will learn that the fish prefer a pH of approximately 6.8. How close to 6.8 does the pH have to be? Well a pH of 7.0 is considered neutral, and a pH of less than 7.0 is considered acidic and a pH of greater than 7.0 is considered basic. Key to understanding this example is that an acid is different than a base and the switch happens at 7.0. Another important clue is knowing that pH is logarithmic, which means that even small changes in pH are really quite large. See What is pH?

Now ask yourself this: What if you went to the Pet Store and they told you that the fish prefer a pH of “like 6.8”? Like 6.8 in what way? A pH of 8.6 could be “like” 6.8 in some ways. Or maybe a pH of 9.8 could be like 6.8 with the number 6 upside down. Clearly this is an extreme example, one which is hopefully a bit funny and memorable. Terms like “approximately” and “substantially” provide more context than you think, where terms such as “like” do little more than narrow it down akin to playing 20 questions.

For those looking for more advanced treatment of this topic please see MPEP 2173.05(b).

Additional Information for Inventors

For more tutorial information please see Invention to Patent 101: Everything You Need to Know. For more information specifically on patent application drafting please see:

The Author

Gene Quinn

Gene Quinn is a Patent Attorney and Editor and President & CEO ofIPWatchdog, Inc.. Gene founded 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 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 Read more.

Discuss this

There are currently 5 Comments comments.

  1. step back January 30, 2016 3:08 pm

    Two thumbs up and three “likes” for this post 😉

  2. Gene Quinn January 30, 2016 3:41 pm

    Thanks Step. I give this talk all the time as part of the patent bar review course and thought it would make an interesting article. Glad you enjoyed it.

  3. Benny January 31, 2016 5:31 am

    Applicant – “…fluid container for maintaining well-being of aquatic life-forms, wherein the pH of the fluid is maintained at a value of 6.8”

    Examiner in office action: “John Doe teaches a container wherein the fluid may be maintained at a pH value between 2 and 12. It would have been obvious to select a value of 6.8”

    I’ve seen OAs almost there.

  4. Michael Lin January 31, 2016 10:43 am

    Good point, Gene – US practitioners should note that in Asia, drafting in relative terms and open-ended ranges may be a fatal flaw which cannot be corrected later. Especially in Korea and China. So if your application is to be filed internationally, be aware of this and be sure to put in firm numbers and ranges in the specification, at least.

  5. Gene Quinn January 31, 2016 11:56 am


    Thanks for this comment. Would you care to draft a similar article for publication with Asia in mind? It would be great to get a comparison article if/when you have time.