The Collaborative International Dictionary of English v.0.48:

Cucurbitaceous \Cu*cur`bi*ta"ceous\ (-b[i^]*t[=a]"sh[u^]s), a.
   [Cf. F. cucurbitac['e].] (Bot.)
   Of, pertaining to, or resembling, a family of plants of which
   the cucumber, melon, and gourd are common examples.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cucurbitaceous
    adj 1: of or relating to plants of the family Cucurbitaceae