fifth

1. The fifth tone of a scale, the dominant. 2. An interval containing five tones, the extremes included. as C-G (the ratio being 2:3). The tonic and the dominant of a key constitute a perfect (or le strictly, major) fifth. To widen the interval by owering the lower (or raising the upper) tone a half-step results in an augmented (or superfluous, extreme, sharp or pluperfect) fifth, as c-g#, or cb-g; to narrow the interval a semitone by raising the lower or lowering the upper tone a half-step results in a diminished (or imperfect, false, flat, minor or defective) fifth. Two parts or voices according to the rules May not progre by perfect fifths either in consecutive or parallel manner, whether the fifths are open or (covered, concealed) hidden (q.v.). Though this rule is the very ABC of harmonic law, it is not justified by science, by history, or by latest practice. Circle of fifths. Vide tremPERAMENT.