False relation

A false relation (also known as cross-relation, non-harmonic relation) is the name of a type of dissonance that sometimes occurs in classical polyphonic music, most commonly in vocal music of the Renaissance. The term describes i) a "chromatic contradiction" between two notes sounding simultaneously, (or in close proximity), in two different voices or parts or ii) in music written before 1600, the occurrence of a tritone between two notes of adjacent chords.