| Noun | 1. | tonic - lime- or lemon-flavored carbonated water containing quininequinine - a bitter alkaloid extracted from chinchona bark; used in malaria therapy soft drink - nonalcoholic beverage (usually carbonated) | |
| 2. | tonic - a sweet drink containing carbonated water and flavoring; "in New England they call sodas tonics"soft drink - nonalcoholic beverage (usually carbonated) | |
| 3. | tonic - (music) the first note of a diatonic scalemusical note, note, tone - a notation representing the pitch and duration of a musical sound; "the singer held the note too long" music - an artistic form of auditory communication incorporating instrumental or vocal tones in a structured and continuous manner | |
| 4. | tonic - a medicine that strengthens and invigorates | |
| Adj. | 1. | tonic - of or relating to or producing normal tone or tonus in muscles or tissue; "a tonic reflex"; "tonic muscle contraction"physiology - the branch of the biological sciences dealing with the functioning of organisms | |
| 2. | tonic - employing variations in pitch to distinguish meanings of otherwise similar words; "Chinese is a tonal language" | |
| 3. | tonic - used of syllables; "a tonic syllables carries the main stress in a word" | |
| 4. | tonic - relating to or being the keynote of a major or minor scale; "tonic harmony"tonal - having tonality; i.e. tones and chords organized in relation to one tone such as a keynote or tonic | |
| 5. | tonic - imparting vitality and energy; "the bracing mountain air"invigorating - imparting strength and vitality; "the invigorating mountain air" | |