Fourth

(forth.) [From A.S. feower, four.] (Numer.) The ordinal of 4.- (Mus.) A distance embracing 3 diatonic intervals. F. are of 3 kinds, viz., the diminished F., comprising a whole tone and 2 semitones; the perfect F., 2 whole tones and a semitone; and the superfluous or extreme sharp F., embracing 3 whole tones. [s. 379]