Musical terms are sometimes very strange history, and their importance seems to be nothing to do with foreign - Greek or Latin root words. This refers to the term of the chromaticity.
If you press the piano key to, and then black on the right side it will start to sound sharp.
The following up - to-sharp is a chromatic semitone. And the chromaticity - following or simultaneous sounding of different pitch, but the same names. For example, d - d-flat, g, g sharp, La - La-sharp, etc.
Origin of the word "chromaticity" from the Greek chroma, meaning color. The ancient Greeks likened seven tones of the diatonic sound - do, re, mi, FA, Sol, La, si - seven major colors of the rainbow. And semitones considered corresponding to different shades.
From the words of the chromaticity formed of various musical concepts. In addition to the chromatic semitone, this chromatic gamma, i.e. gamma, in which movement occurs along the semitones; chromatic signs, what signs of alteration; chromatic intervals, i.e. intervals formed by a chromatically altered degrees of the scale.