ton·ic 
/ˈtɑ:nɪk/ noun
plural ton·ics /ˈtɑ:nɪk/ noun 1 [count, noncount] : a type of water that has bubbles in it, has a bitter taste, and is often used in alcoholic drinks
▪ gin and tonic —called also tonic water 2 [count] a : something that makes you feel healthier and more relaxed — usually singular ▪ A weekend in the mountains was always a tonic for him. ▪ To her, classical music is a tonic.
b : a medicine that brings you back to a normal physical or mental condition
▪ an herbal tonic
c somewhat old-fashioned : a liquid that is used on your hair to make it healthier
▪ a hair tonic 3 [count] music : the main note of a musical key
▪ gin and tonic —called also tonic water
b : a medicine that brings you back to a normal physical or mental condition
▪ an herbal tonic
c somewhat old-fashioned : a liquid that is used on your hair to make it healthier
▪ a hair tonic
