gamutyoudaoicibaDictYouDict[gamut 词源字典]
gamut: [15] Gamut began life as a medieval musical term. The 11th-century French-born musical theorist Guido d’Arezzo devised the ‘hexachord’, a six-note scale used for sightreading music (and forerunner of the modern tonic sol-fa). The notes were mnemonically named ut, re, mi, fa, sol, la (after, according to legend, syllables in a Latin hymn to St John: ‘Ut queant laxis resonāre fibris Mira gestorum famuli tuorum, Solve polluti labii reatum’ – ‘Absolve the crime of the polluted lip in order that the slaves may be able with relaxed chords to praise with sound your marvellous deeds’).

The note below the lowest note (ut) became known as gamma-ut (gamma, the name of the Greek equivalent of g, having been used in medieval notation for the note bottom G). And in due course gamma-ut, or by contraction in English gamut, came to be applied to the whole scale, and hence figuratively to any ‘complete range’ (an early 17th-century development).
[gamut etymology, gamut origin, 英语词源]
gamut (n.)youdaoicibaDictYouDict
1520s, "low G, lowest note in the medieval musical scale" (the system of notation devised by Guido d'Arezzo), a contraction of Medieval Latin gamma ut, from gamma, the Greek letter, used in medieval music notation to indicate the note below the A which began the classical scale, + ut (now do), the low note on the six-note musical scale that took names from syllables sung to those notes in a Latin sapphic hymn for St. John the Baptist's Day:
Ut queant laxis resonare fibris
Mira gestorum famuli tuorum,
Solve pollutis labiis reatum,
Sancte Iohannes.
The ut being the conjunction "that." Gamut also was used for "range of notes of a voice or instrument" (1630s), also "the whole musical scale," hence the figurative sense of "entire scale or range" of anything, first recorded 1620s. When the modern octave scale was set early 16c., si was added, changed to ti in Britain and U.S. to keep the syllables as different from each other as possible. Ut later was replaced by more sonorous do (n.). See also solmization.