# MPEP § 2173.05(a): New Terminology > Federal · Agency guidance · In force URL: https://www.frixlaw.com/law-library/statutes/MPEP_S2173.05(a) ## Section - **Citation:** MPEP § 2173.05(a) - **Heading:** New Terminology - **Jurisdiction:** Federal - **Kind:** Agency guidance - **Status:** In force - **Text as of:** August 14, 2026 - **Source:** Compiled text - **Location:** USPTO MPEP / Chapter 2100 - Patentability / MPEP § 2173.05(a) ## Text I. THE MEANING OF EVERY TERM SHOULD BE APPARENT The meaning of every term used in a claim should be apparent from the prior art or from the specification and drawings at the time the application is filed. Claim language may not be “ambiguous, vague, incoherent, opaque, or otherwise unclear in describing and defining the claimed invention.” In re Packard, 751 F.3d 1307, 1311, 110 USPQ2d 1785, 1787 (Fed. Cir. 2014). Applicants need not confine themselves to the terminology used in the prior art, but are required to make clear and precise the terms that are used to define the invention whereby the metes and bounds of the claimed invention can be ascertained. During patent examination, the pending claims must be given the broadest reasonable interpretation consistent with the specification. In re Morris, 127 F.3d 1048, 1054, 44 USPQ2d 1023, 1027 (Fed. Cir. 1997); In re Prater, 415 F.2d 1393, 162 USPQ 541 (CCPA 1969). See also MPEP § 2111 - § 2111.01 . When the specification states the meaning that a term in the claim is intended to have, the claim is examined using that meaning, in order to achieve a complete exploration of the applicant’s invention and its relation to the prior art. In re Zletz, 893 F.2d 319, 13 USPQ2d 1320 (Fed. Cir. 1989). II. THE REQUIREMENT FOR CLARITY AND PRECISION MUST BE BALANCED WITH THE LIMITATIONS OF THE LANGUAGE Courts have recognized that it is not only permissible, but often desirable, to use new terms that are frequently more precise in describing and defining the new invention. In re Fisher, 427 F.2d 833, 166 USPQ 18 (CCPA 1970). Although it is difficult to compare the claimed invention with the prior art when new terms are used that do not appear in the prior art, this does not make the new terms indefinite. New terms are often used when a new technology is in its infancy or is rapidly evolving. The requirements for clarity and precision must be balanced with the limitations of the language and the science 18 (CCPA 1970). Although it is difficult to compare the claimed invention with the prior art when new terms are used that do not appear in the prior art, this does not make the new terms indefinite. New terms are often used when a new technology is in its infancy or is rapidly evolving. The requirements for clarity and precision must be balanced with the limitations of the language and the science. If the claims, read in light of the specification, reasonably apprise those skilled in the art both of the utilization and scope of the invention, and if the language is as precise as the subject matter permits, the statute ( 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112 , second paragraph) demands no more. Packard, 751 F.3d at 1313, 110 USPQ2d at 1789 ("[H]ow much clarity is required necessarily invokes some standard of reasonable precision in the use of language in the context of the circumstances."). This does not mean that the examiner must accept the best effort of applicant. If the language is not considered as precise as the subject matter permits, the examiner should provide reasons to support the conclusion of indefiniteness and is encouraged to suggest alternatives that would not be subject to rejection. III. TERMS USED CONTRARY TO THEIR ORDINARY MEANING MUST BE CLEARLY REDEFINED IN THE WRITTEN DESCRIPTION Consistent with the well-established axiom in patent law that a patentee or applicant is free to be his or her own lexicographer, a patentee or applicant may use terms in a manner contrary to or inconsistent with one or more of their ordinary meanings if the written description clearly redefines the terms. See, e.g., Process Control Corp. v. HydReclaim Corp., 190 F.3d 1350, 1357, 52 USPQ2d 1029, 1033 (Fed. Cir th the well-established axiom in patent law that a patentee or applicant is free to be his or her own lexicographer, a patentee or applicant may use terms in a manner contrary to or inconsistent with one or more of their ordinary meanings if the written description clearly redefines the terms. See, e.g., Process Control Corp. v. HydReclaim Corp., 190 F.3d 1350, 1357, 52 USPQ2d 1029, 1033 (Fed. Cir. 1999) (“While we have held many times that a patentee can act as his own lexicographer to specifically define terms of a claim contrary to their ordinary meaning,” in such a situation the written description must clearly redefine a claim term “so as to put a reasonable competitor or one reasonably skilled in the art on notice that the patentee intended to so redefine that claim term.”); Hormone Research Foundation Inc. v. Genentech Inc., 904 F.2d 1558, 15 USPQ2d 1039 (Fed. Cir. 1990). Accordingly, when there is more than one meaning for a term, it is incumbent upon applicant to make clear which meaning is being relied upon to claim the invention. Until the meaning of a term or phrase used in a claim is clear, a rejection under 35 U.S.C. 112(b) or pre-AIA 35 U.S.C. 112 , second paragraph is appropriate. It is appropriate to compare the meaning of terms given in technical dictionaries in order to ascertain the accepted meaning of a term in the art. In re Barr, 444 F.2d 588, 170 USPQ 330 (CCPA 1971). See also MPEP § 2111.01 . ## Nearby sections - [MPEP § 2103 Patent Examination Process](https://www.frixlaw.com/law-library/statutes/MPEP_S2103.md) - [MPEP § 2104 Requirements of 35 U.S.C. 101](https://www.frixlaw.com/law-library/statutes/MPEP_S2104.md) - [MPEP § 2104.01 Barred by Atomic Energy Act](https://www.frixlaw.com/law-library/statutes/MPEP_S2104.01.md) - [MPEP § 2105 Patent Eligible Subject Matter — Living Subject Matter](https://www.frixlaw.com/law-library/statutes/MPEP_S2105.md) - [MPEP § 2106 Patent Subject Matter Eligibility](https://www.frixlaw.com/law-library/statutes/MPEP_S2106.md) - [MPEP § 2106.01 [Reserved]](https://www.frixlaw.com/law-library/statutes/MPEP_S2106.01.md) - [MPEP § 2106.02 [Reserved]](https://www.frixlaw.com/law-library/statutes/MPEP_S2106.02.md) - [MPEP § 2106.03 Eligibility Step 1: The Four Categories of Statutory Subject Matter](https://www.frixlaw.com/law-library/statutes/MPEP_S2106.03.md) - [MPEP § 2106.04 Eligibility Step 2A: Whether a Claim is Directed to a Judicial Exception](https://www.frixlaw.com/law-library/statutes/MPEP_S2106.04.md) - [MPEP § 2106.04(a) Abstract Ideas](https://www.frixlaw.com/law-library/statutes/MPEP_S2106.04(a).md) - [MPEP § 2106.04(a)(1) Examples of Claims That Do Not Recite Abstract Ideas](https://www.frixlaw.com/law-library/statutes/MPEP_S2106.04(a)(1).md) - [MPEP § 2106.04(a)(2) Abstract Idea Groupings](https://www.frixlaw.com/law-library/statutes/MPEP_S2106.04(a)(2).md) - [MPEP § 2106.04(a)(3) Tentative Abstract Ideas](https://www.frixlaw.com/law-library/statutes/MPEP_S2106.04(a)(3).md) - [MPEP § 2106.04(b) Laws of Nature, Natural Phenomena & Products of Nature](https://www.frixlaw.com/law-library/statutes/MPEP_S2106.04(b).md) --- Source: Frix Law Library, https://www.frixlaw.com/law-library/statutes/MPEP_S2173.05(a). Check the current official text before relying on it. Not legal advice.