What is the “ordinary and customary meaning” in patent claim interpretation?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

What is the “ordinary and customary meaning” in patent claim interpretation?

The “ordinary and customary meaning” in patent claim interpretation refers to the meaning that a term would have to a person of ordinary skill in the art at the time of the invention. This concept is fundamental to claim construction and is outlined in MPEP 2111.01, which states:

“Under a broadest reasonable interpretation (BRI), words of the claim must be given their plain meaning, unless such meaning is inconsistent with the specification. The plain meaning of a term means the ordinary and customary meaning given to the term by those of ordinary skill in the art at the time of the invention.”

This approach ensures that patent claims are interpreted consistently and objectively, based on the understanding of experts in the relevant field at the time the invention was made.