diabolus in musica/d??ab?l?s ?n ?mu?zi?k?/ /d???ab?l?s ?n ?m(j)u?z?k?/
Mid 19th century. From post-classical Latin diabolus in musica the devil in music (from diabolus devil + classical Latin in + mūsica), more fully mi contra fa, est diabolus in musica ‘mi’ against ‘fa’ is the devil in music, after German Mi contra Fa ist der Teuffel in der Musica; so called as the interval was regarded as unstable and rejected as a consonance by most theorists.