Augmented third

In classical music from Western culture, an augmented third (Playⓘ) is an interval of five semitones.

It may be produced by widening a major third by a chromatic semitone.

[1][3] For instance, the interval from C to E is a major third, four semitones wide, and both the intervals from C♭ to E, and from C to E♯ are augmented thirds, spanning five semitones.

[4] Its inversion is the diminished sixth, and its enharmonic equivalent is the perfect fourth.

Playⓘ The Pythagorean augmented third, E♯+++, is 521.51 cents or 177147:131072, eleven just perfect fifths.