Gamut
Gamut refers to the range of colors that a particular device or color system can represent. It is almost always a subset of the colors visible to the human eye.
Etymology
The word Gamut comes to us originally from music theory, where it now means the full range (all the notes) in a musical scale. The term comes to us from Guido of Arezzo , an Italian music theorist of the 11th century. Among other things, he invented/refined staff musical notation and created a precursor of the do-re-mi scale. His was "ut-re-mi-fa-sol-la" (the scale at the time was six notes instead of seven).
The lowest note of his scale was a G, at the time called by its Greek name Gamma. He combined Gamma and Ut to create the word Gamut, which came to mean the full scale of notes. The word sees common use in the phrase "Run the Gamut."