The Collaborative International Dictionary of English v.0.48:

Kahau \Ka*hau"\, n. [Native name, from its cry.] (Zool.)
   A long-nosed monkey (Nasalis larvatus, formerly
   Semnopithecus nasalis), native of Borneo. The general color
   of the body is bright chestnut, with the under parts,
   shoulders, and sides of the head, golden yellow, and the top
   of the head and upper part of the back brown. Called also
   proboscis monkey. It is now an endangered species. [Written
   also kaha.]
   [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

Nasalis larvatus
    n 1: Borneo monkey having a long bulbous nose [syn: proboscis
         monkey, Nasalis larvatus]