INTERFERANT

interferant. 1. Something that interferes with the proper function of a chemical analysis; specif., a chemical contaminant that renders the results of a blood, breath, or urine test unreliable. 2.Patents. A party to an interference proceeding in the U.S. Patent and Trademark Office. • This term declined in use after the 1960s; today the PTO and courts use the term “contestant.” — Also termed (in sense 2) contestant. See CONTESTANT(3).

[Blacks Law 8th]