Tuber \Tu"ber\, n.[L., a hump. knob; probably akin to tumere to swell. Cf. Tumid.]

1. (Bot.)
   (a) A fleshy, rounded stem or root, usually containing starchy matter, as the potato or arrowroot; a thickened root-stock. See Illust. of Tuberous.
   (b) A genus of fungi. See Truffle.

2. (Anat.) A tuberosity; a tubercle.

Source: Webster's Revised Unabridged Dictionary (1913)