yam

n. 1 a tropical or subtropical climbing plant. B edible starchy tuber of this. 2 us sweet potato. [portuguese or spanish]

n. A large, esculent, farinaceous tuber of various climbing plants of the genus Dioscorea; also, the plants themselves. Mostly natives of warm climates. The plants have netted-veined, petioled leaves, and pods with three broad wings. The commonest species is D. sativa, but several others are cultivated.