(Fr. tonique; Ger. Tonika; It. tonica).
In the major–minor tonal system, the main note of a key (also called its key note), after which the key is named; the name of the scale-step or Degree of that note; the triad built on that note. In music based on one of the church modes, the function of tonic is most closely approached by the Final of that mode.
See also Tonic accent and Tonality.