SIXTH, adjective The first after the fifth; the ordinal of six. SIXTH, noun 1. The sixth part. 2. In music, a hexachord, as interval of two kinds; the minor sixth consisting of three tones and two semitones major, and the major sixth composed of four tones and a major semitone.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI