Minor 7th

The minor 7th, or dominant 7th, is an interval of 10 semitones. It is mildly dissonant — bluesy, with forward momentum, resolving down to the major 6th or up to the octave. It defines the dominant 7th and minor 7th tetrads, marks mixolydian (the ♭7 that distinguishes it from ionian), and is one of the two notes added when expanding a minor triad into the minor pentatonic.