'baboonish' originates from English, specifically the word 'baboon' combined with the suffix '-ish', where 'baboon' referred to the monkey and '-ish' meant 'having the nature of'.

'baboon' came into English via Portuguese 'babuíno' (and French 'babouin') from contact with African languages; the adjective form 'baboonish' is formed by adding the Germanic/Old English-derived suffix '-ish' (from Old English '-isc'). Over time the elements combined into the modern English 'baboonish'.

Initially it referred directly to the animal 'baboon'; over time the adjective also acquired a figurative meaning of 'coarse or uncouth, like a baboon's manner'.