- a large, black gibbon, Hylobates syndactylus, of Sumatra and the Malay Peninsula, having very long arms and the second and third digits partially united by a web of skin: an endangered species.
- a large black gibbon, Hylobates (or Symphalangus) syndactylus, of Sumatra and the Malay Peninsula, having a large reddish-brown vocal sac beneath the chin and the second and third toes united
