Chromatic semitone
A chromatic semitone or augmented unison is the chroma of a diatonic scale. It is also the large step of a p-chromatic scale or the small step of an 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).