neighbour note
A non-chord tone that steps away from a chord tone and returns to the same pitch
In Depth
Also called an auxiliary note, the neighbour note moves by step above or below a chord tone and then returns to it. Upper neighbours move up; lower neighbours move down. Like passing tones, they can be accented or unaccented, and chromatic or diatonic. Incomplete neighbours leave from or return to a different chord tone. Neighbour notes add melodic decoration without disrupting the underlying harmony and are one of the fundamental ornamental figures in all tonal music.
In Baroque ornamentation, the written-out neighbour note gradually replaced the improvised mordent and trill, giving composers more control over the decoration of their melodies.