major

From Wiktionary

major is one of the 1000 most common headwords.

main - major - make

major is on the Academic Word List.

Adjective

Positive
major

(countable) A major change, problem, event, etc. is a big and important one.
We expected the change to cause a lot of problems, but in the end it wasn't as major as we had thought.

Tom Cruise had a major part in the movie. He directed it and acted in it as the main character.
(music) A major musical scale is the usual scale for music in western culture. The major scale starts two notes above the minor and more often sounds happy.
That music could be D minor or F major.

(countable) A major is a subject area that is the main study of a student at a college or university.
My major is Speech-Language Pathology, which is about problems people may have with talking.
(countable) A major is a military rank between captain and lieutenant-colonel.
(countable) A major is a person of the legal age of majority.

Plain form
major

Third-person singular
majors

Past tense
majored

Past participle
majored

Present participle
majoring

If you major in something, you concentrate on a single area of study as a student at a college or university.
My mother majored in English but I will major in psychology.