'antalgic' originates from New Latin/medical Latin, ultimately from Greek 'antálgos' (ἀντάλγος), where 'anti-' meant 'against' and 'algos' meant 'pain'.

'antálgos' was rendered in Late Latin/New Latin as 'antalgicus' and in modern European languages (e.g. French 'antalgique') before entering English usage in medical contexts in the 19th century as 'antalgic'.

Initially it meant 'acting against pain' and this core sense has been retained; it is used both for agents that relieve pain and to describe postures or gaits adopted to avoid pain.