a medicine that invigorates or strengthens

a tonic of sulphur and molasses.

anything invigorating physically, mentally, or morally

His cheerful greeting was a real tonic.

quinine water.

Music . the first degree of the scale; the keynote.

Chiefly Eastern New England . soda pop.

Phonetics . a tonic syllable or accent.

pertaining to, maintaining, increasing, or restoring the tone or health of the body or an organ, as a medicine.

invigorating physically, mentally, or morally.

Physiology, Pathology .

pertaining to tension, as of the muscles.

marked by continued muscular tension

a tonic spasm.

using differences in tone or pitch to distinguish between words that are otherwise phonemically identical

a tonic language.

pertaining to tone or accent in speech.

Phonetics . (of a syllable) bearing the principal stress or accent, usually accompanied by a change in pitch.

Music .

of or pertaining to a tone or tones.

pertaining to or founded on the keynote, or first tone, of a musical scale

a tonic chord.

noun

analeptic , boost , bracer , conditioner , cordial , drug , fillip , invigorator , livener , pick-me-up * , pickup , refresher , restorative , roborant , shot in the arm , stimulant , strengthener , astringent , bracing , catalyst , invigorant , invigorating , medicine , refreshing , soda

adjective

bracing , energizing , exhilarant , exhilarating , innerving , intoxicating , invigorating , refreshing , reinvigorating , renewing , restorative , roborant , stimulating