'thenar' originates from Greek, specifically the word 'thenar' (Ancient Greek: θέναρ/θήναρ), where the root meant 'palm (of the hand)'.

'thenar' passed into Late Latin/Medical Latin as 'thenar' or New Latin anatomical usage and eventually became the modern English anatomical term 'thenar'.

Initially, it meant 'palm' in a general sense, but over time it narrowed to refer specifically to the fleshy area at the base of the thumb (the thenar eminence).