WordNet (r) 3.0 (2006):

yam bean
    n 1: twining plant of Amazon basin having large edible roots
         [syn: yam bean, potato bean, Pachyrhizus tuberosus]
    2: Central American twining plant with edible roots and pods;
       large tubers are eaten raw or cooked especially when young
       and young pods must be thoroughly cooked; pods and seeds also
       yield rotenone and oils [syn: yam bean, Pachyrhizus
       erosus]