'antasthenic' originates from Greek, specifically from the elements 'anti-' and 'asthenēs', where 'anti-' meant 'against' and 'asthenēs' meant 'without strength' or 'weak'.

'antasthenic' developed via New Latin/medical coinage (e.g. 'antiasthenicus') in modern medical English; formed from Greek elements and later adapted into English usage as a rare descriptive adjective.

Initially used in medical contexts to mean 'acting against weakness' (a tonic or restorative); it has retained that basic meaning, though the word is rare in contemporary usage.