The Collaborative International Dictionary of English v.0.48:

Simpai \Sim"pai\, n.[Malay simpei.] (Zool.)
   A long-tailed monkey (Semnopitchecus melalophus) native of
   Sumatra. It has a crest of black hair. The forehead and
   cheeks are fawn color, the upper parts tawny and red, the
   under parts white. Called also black-crested monkey, and
   sinpae.
   [1913 Webster]