The Collaborative International Dictionary of English v.0.48:

dicot \di"cot\ (d[imac]"k[o^]t), n. [by shortening from
   dicotyledon.] (Bot.)
   same as dicotyledon.

   Syn: dicotyledon, dicotyl.
        [PJC]

WordNet (r) 3.0 (2006):

dicot
    n 1: flowering plant with two cotyledons; the stem grows by
         deposit on its outside [syn: dicot, dicotyledon,
         magnoliopsid, exogen]