1. 
[syn: siamang, Hylobates syndactylus, Symphalangus syndactylus]
The Collaborative International Dictionary of English v.0.48:
Siamang \Si"a*mang`\, n. [Malay si[=a]mang.] (Zool.)
   A gibbon (Hylobates syndactylus), native of Sumatra. It has
   the second and third toes partially united by a web.
   [1913 Webster]
WordNet (r) 3.0 (2006):
Hylobates syndactylus
    n 1: large black gibbon of Sumatra having the 2nd and 3rd toes
         partially united by a web [syn: siamang, Hylobates
         syndactylus, Symphalangus syndactylus]