Gimel is from the Latin gemellus, ‘twin’.
A gimel is a form of discant described by Gulielmus Monachus, a writer of the 15th century, as peculiar to the English.
The gimel was sung by two voices, generally at the interval of a third above or below:
Sometimes, however, in a ‘Gimel ad modum de Fauxbourdon,’ the voices were a sixth or even a tenth apart, as in the following example, in which a contratenor ‘bassus’ (i.e., below the tenor) is added.
The treble part was often constructed from a plain-song melody, with embellishments, as in fauxbourdon. Gulielmus gives an example founded on this plain-song:
in which the ‘twin’ voices are a sixth apart, and a contratenor bassus is again added, as in the previous example.
In the 16th century the term gimel was applied to any part of a vocal composition that was temporarily ‘divided.’
Such a gimel occurs in the first treble part of Tye’s Euge Bone mass at the words ‘Pleni sunt cocle’.
In the Sadler part-books at Oxford (MS. Mus. E. 1-5 of the Bodleian Library) maybe be seen an example of a double gimel.
It occurs in Robert White’s 5-part antiphon ‘Justus es, Domine,’ at the words ‘Tribulatio et angustia invenerunt me.’
Both the treble and alto parts are divided for some fifty bars, or nearly a third of the whole composition, and are accompanied by the bass party only.
In the Eton folio MS. 178, the word ‘gemellum’ us used, and is contradicted by the word ‘semellum’ (i.e., single), when the single undivided part is resumed.