'atavic' originates from Latin, specifically the word 'atavus', where 'atavus' meant 'ancestor' or 'forefather'.

'atavic' developed from Medieval Latin 'atavicus' (formed from 'atavus') and from Romance-language adjectives such as Italian 'atavico'; in English the related noun 'atavism' and the adjective 'atavistic' became more common, while 'atavic' appears as a rarer adjective form.

Initially, it meant 'relating to ancestors' (in the sense of descent or lineage), and over time it has come to mean specifically 'relating to atavism' — the reappearance of ancestral or primitive traits.