In music, the adjectives major and minor can describe a scale, key, chord, or interval. For intervals, the terms refer to a difference in their relative width, major referring to notes somewhat further apart; the other terms are classifications based on the use of certain intervals, especially the major or minor third.
Major and minor are frequently referred to in the titles of compositions in their foreign language form, especially in reference to the key of a piece.

Major and minor scales

Relative key
Parallel key
Major/minor (tonal structure)