The Collaborative International Dictionary of English v.0.48:

Vitis \Vi"tis\, prop. n. [L., a vine.] (Bot.)
   A genus of plants including all true grapevines.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Vitis
    n 1: the type genus of the family Vitaceae; woody vines with
         simple leaves and small flowers; includes a wide variety of
         grapes [syn: Vitis, genus Vitis]