major

of greater importance or stature or rank

a major artist

greater in scope or effect

a major contribution

greater in number or size or amount

a major portion (a majority) of the population

of the field of academic study in which one concentrates or specializes

his major field was mathematics

(of a scale or mode) having half steps between the third and fourth degrees and the seventh and eighth degrees

major scales

a commissioned military officer in the United States Army or Air Force or Marines; below lieutenant colonel and above captain

have as one's principal field of study

She is majoring in linguistics