You use minor when you want to describe something that is less important, serious, or significant than other things in a group or situation.

A minor illness or operation is not likely to be dangerous to someone's life or health.

A minor scale is one in which the third note is three semitones higher than the first.

A minor is a person who is still legally a child. In Britain and in most states in the United States, people are minors until they reach the age of eighteen.