TRITONE

in music, the interval formed by three whole steps (e.g., from F to B, containing the whole steps FG, GA, and AB). From the Middle Ages, when it was called the devil in music, until about 1900, the tritone was considered particularly offensive, and its use was either forbidden outright or subject to strict limitations. In musical notation the tritone is written either as an augmented (sharpened) fourth (e.g., FB or CF, in contrast to the perfect fourths FB and CF, respectively) or a diminished (flattened) fifth (e.g., BF or CG, in contrast to the perfect fifths BF and CG, respectively).