Английский Этимологический словарь - major (adj.)

- 13c., from L. major (earlier *magjos), irregular comp. of magnus "large, great." Used in music (of modes, scales, or chords) since 17c., on notion of an interval a half-tone greater than the minor. The military noun is 1643, from Fr., short for sergent-major, originally a higher rank than at present, from M.L. major "chief officer, magnate, superior person," from L. major "an elder, adult," noun use of adj. Major (v.) "focus of studies" is 1924, from noun in sense of "subject of specialization" (1890). The adv. form majorly emerged c.1990.