Darwinist
Concise Oxford English Dictionary © 2008 Oxford University Press:
Darwinism/ˈdɑːwɪnɪzəm/
▶noun the theory of the evolution of species by natural selection, advanced by the English natural historian Charles Darwin (1809–82).
– derivatives
Darwinian noun & adjective,
Darwinist noun & adjective.
Darwinian noun & adjective,
Darwinist noun & adjective.
'Darwinist' also found in these Oxford entries:

