caul

Speculative, Uncertain. There are two main potential sources, and it is not impossible that two different words have been here conflated. One suggestion is that the word is related to to OE caul, cawl, a basket, container or net. This word is itself of uncertain origin (and is not attested in the OE period in a clothing-related sense); it is discussed in the OED under cawl n. where examples from modern Cornish dialect are given (in the sense 'fishing-basket'), but incorrectly, since these do not reflect OE at all but are a borrowing into Cornish dialect from the Cornish word cawl, which is < Latin cauellum 'small hollow' (the Latin word may independently be the source of the OE word). Another suggestion is that the word is a borrowing from French: OED suggests: 'a. F. cale a kind of small cap or head-dress', [s.v. 'caul, n.1', OED, 2nd ed. (1989)]; but the MED responds: 'OF cale of the 15th century is either a back-formation from calotte (Gamillscheg) or a borrowing from English' [s.v. 'calle', MED]. The MED here is obviously wrong about cale being a back-formation from calotte, and the editors were apparently unaware of the copious early examples of the word in Anglo-French sources (principally glosses) of the 12th-13th centuries (e.g. present citation 1). The French word has been suggested to be aphetic from écale 'husk, shell of a nut', also 'cup' (due to the shape), which is Old French escale < Frankish *skala (the exact cognate of OE scealu, MdE 'shell').