tonic (adj.)

1640s, "relating to or characterized by muscular tension," from Greek tonikos "of stretching," from tonos "a stretching," from PIE root *ten- "to stretch." The meaning "maintaining the healthy firmness of tissues" is recorded from 1680s, first extended 1756 to "having the property of restoring to health." Related: Tonical (1580s).

tonic (n.1)

"a tonic medicine," 1799, from tonic (adj.). From 1873 (in gin and tonic) as short for tonic water (1861 as a commercial product, water infused with quinine), so called because held to aid digestion and stimulate appetite.

tonic (n.2)

in the musical sense, 1760, short for tonic note, from tone (n.) in the musical sense + -ic. Related: Tonicity.

updated on April 17, 2017

Definitions of tonic from WordNet
tonic (adj.)
of or relating to or producing normal tone or tonus in muscles or tissue;
a tonic reflex
tonic muscle contraction
tonic (adj.)
employing variations in pitch to distinguish meanings of otherwise similar words;
Synonyms: tonal
tonic (adj.)
(used of syllables) bearing the principle stress, usually accompanied by a change in pitch;
a tonic syllables carries the main stress in a word
Synonyms: accented
tonic (adj.)
relating to or being the keynote of a major or minor scale;
tonic harmony
tonic (adj.)
imparting vitality and energy;
Synonyms: bracing / brisk / fresh / refreshing / refreshful
tonic (n.)
lime- or lemon-flavored carbonated water containing quinine;
Synonyms: tonic water / quinine water
tonic (n.)
a sweet drink containing carbonated water and flavoring;
in New England they call sodas tonics
Synonyms: pop / soda / soda pop / soda water
tonic (n.)
(music) the first note of a diatonic scale;
Synonyms: keynote
tonic (n.)
a medicine that strengthens and invigorates;
Synonyms: restorative
Etymologies are not definitions. From, not affiliated with etymonline.