a very agile black gibbon (Symphalangus syndactylus) of the Malay Peninsula and Sumatra
Origin:
Malay
See siamang in American Heritage Dictionary 4
noun
A large black gibbon (Symphalangus syndactylus or Hylobates syndactylus) of Sumatra and the Malay Peninsula, having an inflatable throat sac and a web of skin joining the second and third toes.