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.
Hylobates syndactylus n : large black gibbon of Sumatra having the 2nd and 3rd toes partially united by a web [syn: {siamang}, {Symphalangus syndactylus}]