Main Entry: ²tonic

Function: noun

Date: 1797

1 : the first tone of a major or minor scale : keynote
2 a : an agent (as a drug) that increases body tone b : one that invigorates, restores, refreshes, or stimulates <a day in the country was a tonic for him> c : a liquid preparation for the scalp or hair d chiefly New England : a carbonated flavored beverage e : tonic water
3 : a voiced sound