1590s, "of or pertaining to the people of Frisia," the lowland coast of the North Sea and nearby islands (Old English Frysland, Freslond; adjective Freisisc), named for the Germanic tribe whose name was Latinized as Frisii," which perhaps originally meant "curly-headed" (compare Old Frisian frisle "curly hair"). The native form of the people name is Old English Frysan/Fresan (plural). Cognate with Old Frisian Frise, Middle Dutch Vriese, Old High German Friaso). As a noun from c.1600, "West Germanic language spoken in Friesland." It is closely related to Dutch and Old English.