Nouns

(n)majora commissioned military officer in the United States Army or Air Force or Marines; below lieutenant colonel and above captain
(n)majora university student who is studying a particular field as the principal subject“she is a linguistics major”
(n)majorthe principal field of study of a student at a university“her major is linguistics”

Verbs

(v)majorhave as one's principal field of study“She is majoring in linguistics”

Adjectives

(a)majorof greater importance or stature or rank“a major artist”, “a major role”, “major highways”
(a)majorgreater in scope or effect“a major contribution”, “a major improvement”, “a major break with tradition”, “a major misunderstanding”
(a)majorgreater in number or size or amount“a major portion (a majority) of the population”, “Ursa Major”, “a major portion of the winnings”
(a)majorof the field of academic study in which one concentrates or specializes“his major field was mathematics”
(a)major(of a scale or mode) having half steps between the third and fourth degrees and the seventh and eighth degrees“major scales”, “the key of D major”
(a)majorof greater seriousness or danger“a major earthquake”, “a major hurricane”, “a major illness”
(a)majorof full legal age
(s)majorof the elder of two boys with the same family name“Jones major”