The Collaborative International Dictionary of English v.0.48:

Cacajao \Ca*ca*j[~a]o"\, n. [Pg.] (Zool)
   A South American short-tailed monkey (Pithecia
   melanocephala syn. Brachyurus melanocephala). [Written
   also cacajo.]
   [1913 Webster]

WordNet (r) 3.0 (2006):

Cacajao
    n 1: uakaris [syn: Cacajao, genus Cacajao]