The Collaborative International Dictionary of English v.0.48:

Cowhage \Cow"hage\ (kou"h[asl]j), n. [Cf. Hind. kaw[=a]nch,
   ko[=a]nch.] (Bot.)
   A leguminous climbing plant of the genus Mucuna, having
   crooked pods covered with sharp hairs, which stick to the
   fingers, causing intolerable itching. The spicul[ae] are
   sometimes used in medicine as a mechanical vermifuge.
   [Written also couhage, cowage, and cowitch.]
   [1913 Webster]