Notes that don't belong to the traditional scale are known as?

Notes that don't belong to the traditional scale are known as "non-scale tones" or "chromatic notes." These notes can include accidentals, such as sharps and flats, which alter the pitch of the scale degrees. They are often used to create tension, color, or expressiveness in music. Additionally, in some contexts, they may be referred to as "blue notes" in jazz and blues, which add a unique emotional quality.