The hen in Chaucer's Nun's Priest's Tale, and in the tale of Reynard the Fox (fourteenth century). So called from the partlet or loose collar of “the doublet,” referring to the frill-like feathers round the neck of certain hens. (A partlet was a ruff worn in the 16th century by women.)
In the barn the tenant cock Close to partlet perched on high.
Sister Partlet with her hooded head, allegorises the cloistered community of nuns in Dryden's Hind and Panther, where the Roman Catholic clergy are likened to barnyard fowls.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894