the entire scale or range

This may be the single most interesting English etymology I've ever looked up. Incidentally, I looked it up because I was at a conference and a speaker (otherwise very good, with a very interesting talk) kept using the word, and kept mispronouncing it "gambit."

From Dictionary.com:

gam⋅ut

[gam-uht]
–noun
1. the entire scale or range: the gamut of dramatic emotion from grief to joy.
2. Music. a. the whole series of recognized musical notes. b. the major scale.

Origin:
1425–75; late ME gamma ut, equiv. to gamma, used to represent the first or lowest tone (G) in the medieval scale + ut (later do); the notes of the scale (ut, re, mi, fa, sol, la, si) being named from a Latin hymn to St. John the Baptist: Ut queant laxis resonare fibris. Mira gestorum famuli tuorum, Solve polluti labii reatum, Sancte Iohannes