'adaptionism' originates from the English word 'adaptation,' which comes from the Latin word 'adaptare,' meaning 'to fit or adjust.'

'adaptation' evolved from the Latin 'adaptare' through Old French 'adapter,' eventually becoming the modern English word 'adaptation,' and subsequently 'adaptionism' in scientific discourse.

Initially, 'adaptation' referred to the process of fitting or adjusting, but in scientific contexts, it evolved to describe the process by which organisms become better suited to their environment.