Chromatic semitone
In scale theory, the chromatic semitone or the augmented unison is the chroma of the diatonic scale. It is also the large step of the p-chromatic scale or the small step of the m-chromatic scale.
In just intonation, an interval may be classified as a chromatic semitone if it is reasonably mapped to 0\7 and 1\12 (precisely zero steps of the diatonic scale and one step of the chromatic scale).