quatreble
/ˈkwatrəbl/Now historical
noun
Early Music. In improvised descant: a voice part pitched higher than the treble, beginning and ending a twelfth above the plainsong. Compare quinible. Now historical.
Origin
Late Middle English (in an earlier sense). From Anglo-Norman quatreble fourfold, variant of quadruple quadruple, either after treble or after quatre four. The some forms could alternatively be explained as alterations of quadruple after -ible.