definition of
tonic

[1] #1 tonic n. [tonic water, quinine water] lime- or lemon-flavored carbonated water containing quinine. wn

[2] #2 tonic a. of or relating to or producing normal tone or tonus in muscles or tissue; "a tonic reflex"; "tonic muscle contraction". wn

[3] #3 tonic n. [pop, soda, soda pop, soda water] a sweet drink containing carbonated water and flavoring; "in New England they call sodas tonics". wn

[4] #4 tonic a. [tonal] employing variations in pitch to distinguish meanings of otherwise similar words; "Chinese is a tonal language". wn

[5] #5 tonic n. [keynote] (music) the first note of a diatonic scale. wn