Contrayerva \Con`tra*yer"va\, n. [Sp. contrayerba, literally, a counter herb, hence, an antidote for poison, fr. l. contra + herba herb.] (Bot.) A species of {Dorstenia} ({D. Contrayerva}), a South American plant, the aromatic root of which is sometimes used in medicine as a gentle stimulant and tonic.