'atavistic' originates from Latin, specifically the word 'atavus', where 'atavus' meant 'ancestor'.

'atavistic' changed from the Medieval Latin/Latin word 'atavismus' (from 'atavus') and the noun 'atavism', and eventually developed into the English adjective 'atavistic' and the adverb 'atavistically'.

Initially it meant 'relating to an ancestor', but over time it evolved into its current meaning of 'relating to a reversion to ancestral or primitive traits'.