adverse witness is a noun meaning "a witness whose relationship to the opposing party is such that his or her testimony may be prejudiced against the opposing party". It carries one recorded sense.
a witness whose relationship to the opposing party is such that his or her testimony may be prejudiced against the opposing party
“a hostile witness can be asked leading questions and cross-examined”
Definitions, synonyms and semantic relations for adverse witness come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.