tonic

¹ American  

[ton-ik] / ˈtɒn ɪk /

noun

1. a medicine that invigorates or strengthens.

   a tonic of sulphur and molasses.

2. anything invigorating physically, mentally, or morally.

   His cheerful greeting was a real tonic.

   Synonyms:

   pickup, bracer, restorative, stimulant

3. quinine water.

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

5. Chiefly Eastern New England. soda pop.

6. Phonetics. a tonic syllable or accent.

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adjective

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

2. invigorating physically, mentally, or morally.

3. Physiology, Pathology.

   1. pertaining to tension, as of the muscles.

   2. marked by continued muscular tension.

      a tonic spasm.

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

   a tonic language.

5. pertaining to tone or accent in speech.

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

7. Music.

   1. of or relating to a tone or tones.

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

      a tonic chord.

-tonic ² American  

1. a combining form occurring in adjectives that correspond to nouns ending in -tonia:

   catatonic.

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tonic British  

/ ˈtɒnɪk /

noun

1. a medicinal preparation intended to improve and strengthen the functioning of the body or increase the feeling of wellbeing

2. anything that enlivens or strengthens

   his speech was a tonic to the audience

3. Also called: tonic water.  a mineral water, usually carbonated and containing quinine and often mixed with gin or other alcoholic drinks

4. music

   1. the first degree of a major or minor scale and the tonal centre of a piece composed in a particular key

   2. a key or chord based on this

5. a stressed syllable in a word

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adjective

1. serving to enliven and invigorate

   a tonic wine

2. of or relating to a tone or tones

3. music of or relating to the first degree of a major or minor scale

4. of or denoting the general effect of colour and light and shade in a picture

5. physiol of, relating to, characterized by, or affecting normal muscular or bodily tone

   a tonic spasm

6. of or relating to stress or the main stress in a word

7. denoting a tone language

Regionalisms

See soda pop.

Other Word Forms

• antitonic adjective
• nontonic adjective
• pretonic noun
• tonically adverb

Etymology

Origin of tonic¹

First recorded in 1640–50, tonic is from the Greek word tonikós pertaining to stretching or tones. See tone, -ic

Origin of -tonic²

tonic

Example Sentences

Reaching the final was a welcome tonic for Guardiola following the frustration of blowing a two-goal lead in a 2-2 draw at Tottenham on Sunday that delivered a major blow to their title challenge.

From Barron's • Feb. 4, 2026

The outlook, a good tonic for our dangerously fractious times, is worth recovering.

From The Wall Street Journal • Dec. 22, 2025

But numerous online shoppers post product reviews that go further, referring to it as a tonic.

From Salon • Dec. 15, 2025

One seller was found promoting them as a tonic for mothers who have just given birth and as a medicine for combating coughs.

From BBC • Dec. 11, 2025

She opened the top bureau drawer and examined the bottles which constituted the medicine chest of the house— paregoric, Pain Killer, Lydia Pinkham, iron wine tonic, Hall’s Cream Salve, Epsom salts, castor oil, ammonia.

From "East of Eden" by John Steinbeck