blue note

noun, Jazz.
1.
a flatted note, especially the third or the seventh degree of the scale, recurring frequently in blues and jazz as a characteristic feature.
Origin
1925-30
British Dictionary definitions for blue note

blue note

noun
1.
(jazz) a flattened third or seventh, used frequently in the blues
Slang definitions & phrases for blue note

blue note

noun phrase

A flatted note of the sort common in lues musi (1890s+ Musicians)