E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Gammut, or Gamut (g hard).
It is gamma ut, ut being the first word in the Guido-von-Arrezzo scale of ut, re, mi, fa, sol, la. In the eleventh century the ancient scale was extended a note below the Greek proslambanomy note (our A), the first space of the bass staff. The new note was termed (gamma), and when ut was substituted by Arrezzo the supernumerary note was called gamma or ut, or shortly gamm uti.e.Gut. The gammut, therefore, properly means the diatonic scale beginning in the bass clef with G.