Webster's 1828 Dictionary
CONTRAYERVA
n.[L., an antidote for poison, or in general, an antidote. ] The genus of plants, Dorstenia; all low herbaceous plants, natives of the warm climates of America, and useful as diaphoretics.
Webster's 1913 Dictionary
CONTRAYERVA
Con `tra *yer "va, n. Etym: [Sp. contrayerba, literally, a counter herb, hence, an antidote for poison, fr. l. contra + herba herb. ] (Bot. )
Defn: 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.
The Wordsmith Dictionary