Tertian

In music theory, tertian (Latin:tertianus, "of or concerning thirds") describes any piece, chord, counterpoint etc. constructed from the intervals of (major and minor) thirds. An interval such as that between the notes A and C encompasses 3 semitone intervals (A-B♭-B♮-C) and is termed a minor third while one such as that between C and E encompasses 4 semitones (C-D♭-D♮-E♭-E♮) and is called a major third. Tertian harmony (also called tertiary harmony) principally uses chords based on thirds; the term is typically used to contrast with quartal and quintal harmony which uses chords based on fourths or fifths.