The Locrian mode is the only modern diatonic mode in which the
tonic triad is a
diminished chord (
flattened fifth), which is considered very
dissonant. This is because the interval between the
root and fifth of the chord is a
diminished fifth. For example, the tonic triad of B Locrian is made from the notes B, D, F. The root is B and the
dim 5th is F. The diminished-fifth interval between them is the cause for the chord's striking dissonance. : { \override Score.TimeSignature #'stencil = ##f \relative c' { \clef treble \time 7/4 b4^\markup { B Locrian mode } c d e f g a b2 } } The name "Locrian" is borrowed from music theory of
ancient Greece. What is now called the
Locrian mode, however, was what the Greeks called the
diatonic Mixolydian tonos. The Greeks used the term "Locrian" as an alternative name for their "
Hypodorian", or "common" tonos, with a scale running from
mese to
nete hyperbolaion, which in its diatonic genus corresponds to the modern
Aeolian mode. In his reform of modal theory,
Glarean named this division of the octave "hyperaeolian" and printed some musical examples (a three-part polyphonic example specially commissioned from his friend
Sixtus Dietrich, and the Christe from the
Missa de Sancto Antonio by Pierre de La Rue|), although he did not accept hyperaeolian as one of his twelve modes. The term "Locrian" as equivalent to Glarean's
hyperaeolian or the ancient Greek (diatonic)
mixolydian, however, was not used until the 19th century. ==Use==