'anti-tonic' originates from Greek elements: the prefix 'anti-' meaning 'against' and the Greek word 'tonos' meaning 'tone' or 'stretch', combined with the English/French-derived adjective 'tonic'.

'tonic' entered English via Middle French 'tonique' and Late Latin from Greek 'tonos'; the prefix 'anti-' is from Greek 'anti-' meaning 'against'. In Modern English the combination 'anti-' + 'tonic' produced the compound 'anti-tonic'.

Initially used in contexts meaning 'against a tonic' (often pharmacological, i.e. counteracting restorative tonics); over time it has also been applied metaphorically in music and linguistics to mean 'opposed to the tonic' (contrastive to the principal tone).