A borrowed chord (also called mode mixture, modal mixture, substituted chord, modal interchange, or mutation) is a chord borrowed from the parallel key (minor or major scale with the same tonic). Borrowed chords are typically used as "color chords", providing harmonic variety through contrasting scale forms, which are major scales and the three forms of minor scales. Chords may also be borrowed from other parallel modes besides the major and minor mode, for example D Dorian with D major. The mixing of the major and minor modes developed in the Baroque period.
Borrowed chords are distinguished from modulation by being brief enough that the tonic is not lost or displaced, and may be considered brief or transitory modulations and may be distinguished from secondary chords as well as altered chords. According to Sheila Romeo, "[t]he borrowed chord suggests the sound of its own mode without actually switching to that mode."
