|Origin:||tonikos, from tonos; TONE1|
1 [uncountable and countable] also tonic waterDFD
a clear bitter-tastingdrink that you can mix with alcoholic drinks such as gin or vodka:
She sat and sipped a gin and tonic.
a drink that you have as a medicine to give you more energy or strength when you feel tired:
A lot of people need a tonic at the end of the winter.
3 [countable usually singular] British English
something that makes you feel happy and full of energy:
A weekend by the sea was the perfect tonic.
a liquid that you put on your hair or skin to improve it and make it more healthy:
a herbal skin tonic
5 [countable usually singular] technicalAPM
the first note in a musical scale of eight notes