1590s, "a Norwegian," from obsolete Dutch Noorsch (adj.) "Norwegian," a reduced form of noordsch "northern, nordic," from noord "north" (see north). Also in some cases borrowed from cognate Danish or Norwegian norsk. As a language of the north (spoken and written in Norway, Iceland, etc.), from 1680s. Old Norse attested from 1844. An Old English word for "a Norwegian" was Norðman. As an adjective from 1768.
In Old French, Norois as a noun meant "a Norse, Norseman," also "action worth of a man from the North (i.e. usually considered as deceitful)" [Hindley, et. al.]; as an adjective it meant "northern, Norse, Norwegian," also "proud, fierce, fiery, strong."