- pertaining to tension, as of the muscles.
- marked by continued muscular tension: a tonic spasm.
Origin of tonic
Synonyms for tonic
Regional variation note
- the first degree of a major or minor scale and the tonal centre of a piece composed in a particular key
- a key or chord based on this
Word Origin for tonic
1640s, "relating to or characterized by muscular tension," from Greek tonikos "of stretching," from tonos "a stretching" (see tenet). The meaning "maintaining the healthy firmness of tissues" is recorded from 1680s, first extended 1756 to "having the property of restoring to health."
"a tonic medicine," 1799, from tonic (adj.).