tonic (Noun) — Lime- or lemon-flavoured carbonated water containing quinine.
tonic (Noun) — A sweet drink containing carbonated water and flavouring. ex. "in New England they call sodas tonics"
tonic (Noun) — (music) the first note of a diatonic scale.
tonic (Noun) — A medicine that strengthens and invigorates.
tonic (Adjective) — (physiology) of or relating to or producing normal tone or tonus in muscles or tissue. ex. "a tonic reflex" ex. "tonic muscle contraction"
tonic (Adjective) — Employing variations in pitch to distinguish meanings of otherwise similar words. ex. "Chinese is a tonic language"
tonic (Adjective) — (phonetics) of a syllable, having the main stress. ex. "a tonic syllable carries the main stress in a word"
tonic (Adjective) — Relating to or being the keynote of a major or minor scale. ex. "tonic harmony"
tonic (Adjective) — Imparting vitality and energy. ex. "the tonic mountain air"