tonic Pronunciation: /ˈtɒnɪk/Translate tonic | into German | into Italian | into Spanish French translation of tonicn 1 (also tonic water) eau (f) tonique a gin and tonic = un gin tonic 2 [Med] remontant (m)tonic in other Oxford dictionaries Definition of tonic in the British & World English dictionary Definition of tonic in the US English dictionary