The Collaborative International Dictionary of English v.0.48:

Caryopsis \Car`y*op"sis\, n.; pl. Caryopses. [NL., fr. gr. ?
   hut, kernel + ? sight, form.] (Bot.)
   A one-celled, dry, indehiscent fruit, with a thin membranous
   pericarp, adhering closely to the seed, so that fruit and
   seed are incorporated in one body, forming a single grain, as
   of wheat, barley, etc.
   [1913 Webster]

WordNet (r) 3.0 (2006):

caryopsis
    n 1: dry seed-like fruit produced by the cereal grasses: e.g.
         wheat, barley, Indian corn [syn: grain, caryopsis]