The Collaborative International Dictionary of English v.0.48:

Zati \Za"ti\ (z[aum]"t[-e]), n. (Zool.)
   A species of macaque (Macacus pileatus) native of India and
   Ceylon. It has a crown of long erect hair, and tuft of
   radiating hairs on the back of the head. Called also capped
   macaque.
   [1913 Webster]