Blue note

In jazz and blues, a blue note is a note that—for expressive purposes—is sung or played at a slightly different pitch from standard. Typically the alteration is between a quartertone and a semitone, but this varies depending on the musical context.

Quotes about the blue note

• The so-called “wrong notes” people might tell you to not play are sometimes the ones that sound amazing against the riff and really make your playing stand out. Take Marty's playing on Megadeth's "Rust In Peace." He is throwing in all kinds of exotic scales and interesting note choices all over the place.
  • Dave Reffett of Guitar World (June 1, 2015) [1]