A witness who provides testimony that contradicts or disputes the evidence given by another witness.
From counter- (against) + witness (one who sees or testifies). A legal term developed from the need to describe opposing testimony in court proceedings.
In trials, when two witnesses tell completely different stories about what happened, each becomes the other's counterwitness—and sometimes the truth depends on which one the jury believes, which shows how unreliable memory and perception can be.
Complete word intelligence in one call. Free tier — 50 lookups/day.