1. [n]  small arboreal monkey of tropical South America with long hair and bushy nonprehensile tail
2. [n]  Japanese beverage from fermented rice usually served hot
3. [n]  British writer of short stories (1870-1916)

SAKI is a 4 letter word that starts with S.

1. \Sa"ki\ (s[=a]"k[i^]), n. [Cf. F. & Pg. saki; probably from
   the native name.] (Zo["o]l.)
   Any one of several species of South American monkeys of the
   genus {Pithecia}. They have large ears, and a long hairy tail
   which is not prehensile.
   
   Note: The black saki ({Pithecia satanas}), the white-headed
         ({P. leucocephala}), and the red-backed, or
         hand-drinking, saki ({P. chiropotes}), are among the
         best-known.
   
   

2. \Sa"ki\ (s[aum]"k[-e]), n.
   The alcoholic drink of Japan. It is made from rice.