a unit used in music to describe the ratio in frequency between notes. Two notes differ by one minor sixth if the higher note has frequency exactly 8/5 times the frequency of the lower one, or by a major sixth if the higher note has frequency exactly 5/3 times the frequency of the lower one. On the standard 12-tone scale the minor sixth is approximated (roughly) by 8 half steps, corresponding to a frequency ratio of 22/3 = 1.5874; the major sixth is approximated by 9 half steps, corresponding to a frequency ratio of 23/4 = 1.6818.
The sixth degree of the diatonic scale. Also, the interval formed by a given tone and the sixth tone above or below it, e.g. c up to a, or c down to e. Intervals of the sixth may be major, minor, diminished, or augmented.