The half diminished scale is a seven-note musical scale. It is more commonly known as the Locrian ♮2 scale or the Aeolian ♭5 scale, names that avoid confusion with the diminished scale and the half-diminished seventh chord (minor seventh, diminished fifth). It is the sixth mode of the ascending melodic minor scale.
In the key of B♭, the half-diminished scale built on C is associated with Cm, which functions as a ii chord in minor (see chord-scale system).
In Western classical music theory, the minor scale refers to three scale patterns – the natural minor scale (or Aeolian mode), the harmonic minor scale, and the melodic minor scale (ascending or descending).
These scales contain all three notes of a minor triad: the root, a minor third (rather than the major third, as in a major triad or major scale), and a perfect fifth (rather than the diminished fifth, as in a diminished scale or half diminished scale).
View the full Wikipedia page for Natural minor