'counter-idea' is a compound of 'counter' and 'idea'. 'counter' originates from Old French, specifically the word 'contre', where 'contre' meant 'against'. 'idea' originates from Greek, specifically the word 'ἰδέα' (idéa), where 'ἰδέ-' (ide-) meant 'form' or 'appearance'.

'counter' entered English via Old French 'contre' and Middle English 'countre'; 'idea' passed into English via Latin and Old French from Greek 'ἰδέα'; the compound 'counter-idea' is a modern English formation (chiefly 20th century onward) combining the prefix/form 'counter-' with 'idea'.

Initially, 'idea' meant 'form' or 'appearance' in Greek, but over time it evolved into the modern sense 'a thought, notion, or suggestion'; 'counter' has long carried the sense 'against', and the compound now means 'an opposing or alternative idea'.