The Collaborative International Dictionary of English v.0.48:

Syconium \Sy*co"ni*um\, Syconus \Sy*co"nus\, n. [NL., fr. Gr. ?
   the fig.] (Bot.)
   A collective fleshy fruit, in which the ovaries are hidden
   within a hollow receptacle, as in the fig.
   [1913 Webster]

WordNet (r) 3.0 (2006):

syconium
    n 1: the fleshy multiple fruit of the fig consisting of an
         enlarged hollow receptacle containing numerous fruitlets