What is the opposite of Augmented?

The opposite of Augmented includes: Diminished.

Augmented

An interval that has been widened by one semitone beyond its major or perfect form.

About Augmented

An augmented intervalIntervalThe distance in pitch between two notes.View full entry → is created by expanding a major or perfect interval by one semitoneSemitoneThe smallest interval in standard Western musicView full entry →. For example, a major thirdMajor ThirdAn interval spanning four semitones, often perceived as bright, warm, and optimistic in character.View full entry → (four semitones, C to E) becomes an augmented thirdThirdAn interval spanning three diatonic scale degreesView full entry → (five semitones, C to E♯), and a perfect fifthPerfect FifthAn interval of seven semitonesView full entry → (seven semitones, C to G) becomes an augmented fifthFifthThe interval spanning five scale degrees, most commonly the perfect fifth.View full entry → (eight semitones, C to G♯).