Origin and history of wisp

late 13c., "handful or bundle of hay, grass, etc.," used for burning or cleaning or as a cushion; a word of uncertain origin, perhaps from an unrecorded Old English word cognate with Norwegian and Swedish visp "wisp," all of unknown origin.

It is sometimes said to be connected with whisk (which also is sometimes strenuously denied) or with Middle Low German and Middle Dutch wispel "a measure of grain." The meaning "thin, filmy portion" is attested by 1836. As a verb by 1590s, "rub down with a wisp."