Chromatic in the context of "Subject (music)"

Chromaticism is a compositional technique interspersing the primary diatonic pitches and chords with other pitches of the chromatic scale. In simple terms, within each octave, diatonic music uses only seven different notes, rather than the twelve available on a standard piano keyboard. Music is chromatic when it uses more than just these seven notes.

Chromaticism is in contrast or addition to tonality or diatonicism and modality (the major and minor, or "white key", scales). Chromatic elements are considered, "elaborations of or substitutions for diatonic scale members".

In music theory, a chromatic fourth, or passus duriusculus, is a melody or melodic fragment spanning a perfect fourth with all or almost all chromatic intervals filled in (chromatic line). The quintessential example is in D minor with the tonic and dominant notes as boundaries:

The chromatic fourth was first used in the madrigals of the 16th century. The Latin term itself—"harsh" or "difficult" (duriusculus) "step" or "passage" (passus)—originates in Christoph Bernhard's 17th-century Tractatus compositionis augmentatus (1648–49), where it appears to refer to repeated melodic motion by semitone creating consecutive semitones. The term may also relate to the pianto associated with weeping. In the Baroque, Johann Sebastian Bach used it in his choral as well as his instrumental music, in the Well-Tempered Clavier, for example (the chromatic fourth is indicated by the red notes):

In music theory, the syntonic comma, also known as the chromatic diesis, the Didymean comma, the Ptolemaic comma, or the diatonic comma, is a small comma type interval between two musical notes, equal to the frequency ratio ⁠81/80⁠ (= 1.0125) (around 21.51 cents). Two notes that differ by this interval would sound different from each other even to untrained ears, but would be close enough that they would be more likely interpreted as out-of-tune versions of the same note than as different notes. The comma is also referred to as a Didymean comma because it is the amount by which Didymus corrected the Pythagorean major third (⁠81/64⁠, around 407.82 cents) to a justly intoned major third (⁠5/4⁠, around 386.31 cents).

The word "comma" came via Latin from Greek κόμμα, from earlier *κοπ-μα = "a thing cut off", or "a hair", as in "off by just a hair".