'antidotical' originates from Late Latin, specifically the word 'antidotum', which in turn comes from Greek 'antídōton', where 'anti-' meant 'against' and the root (from Greek verbal forms meaning) 'to give' indicated something 'given against' (i.e., given to counteract).

'antidotical' changed from Greek 'antídōton' to Latin 'antidotum', passed into Old French/Medieval Latin forms and Middle English as 'antidot'/'antidotum', and eventually developed into the Modern English adjective 'antidotical' and the adverb 'antidotically'.

Initially, it meant 'given against' (specifically a substance given against poison); over time it evolved into the current meaning of 'serving as a remedy or countermeasure' and, by extension, 'neutralizing or counteracting' in both literal and figurative uses.