 The inversion of this, a diminished fifth, resolves inward to a major or minor third (the second measure below).The diminished fifth is often called a tritone in modern tonal theory, but functionally and notationally it can only resolve inwards as a diminished fifth and is therefore not reckoned a tritone—that is, an interval composed of three adjacent whole tones—in mid-renaissance (early 16th-century) music theory.The tritone is also one of the defining features of the Locrian mode, being featured between the and fifth scale degrees.