- a fossil bipedal primate with both apelike and human characteristics, found in Pliocene and lower Pleistocene deposits (circa 4 million to 1 million years old) in Africa.
- Genus Australopithecus, family Hominidae: several species, including the lightly built A. africanus, which is thought to be the immediate ancestor of the human genus Homo. The more heavily built forms (often placed in the genus Paranthropus), such as A. robustus and A. boisei, were probably evolutionary dead ends
Pronunciation: /-ˌsēn, -ˌsīn/noun & adjective
modern Latin, from Latin australis 'southern' (see austral) + Greek pithēkos 'ape'