chromatic

The chromatic scale includes all twelve semitones within an octave, moving by half steps. When a passage is described as chromatic, it uses notes outside the current key, adding colour, tension, or complexity to the harmony or melody. Chromaticism increased dramatically from the Baroque through the Romantic era. Wagner's music pushed chromaticism to its limits, blurring the sense of key so thoroughly that it paved the way for atonality. In jazz, chromatic passing tones and approach notes add sophistication to improvised lines.