The Collaborative International Dictionary of English v.0.48:

Capitate \Cap"i*tate\ (k[a^]p"[i^]*t[asl]t), a. [L. capitatus
   fr. caput head.]
   1. Headlike in form; also, having the distal end enlarged and
      rounded, as the stigmas of certain flowers.
      [1913 Webster]

   2. (Bot.) Having the flowers gathered into a head.
      [1913 Webster]

WordNet (r) 3.0 (2006):

capitate
    adj 1: being abruptly enlarged and globose at the tip
    n 1: the wrist bone with a rounded head shape that articulates
         with the 3rd metacarpus [syn: capitate, capitate bone,
         os capitatum]