Definition of boreal :
1. Designating or pertaining to a terrestrial division consisting of the northern and mountainous parts of both the Old and the New World; -- equivalent to the Holarctic region exclusive of the Transition, Sonoran, and corresponding areas. The term is used by American authors and applied by them chiefly to the Nearctic subregion. The Boreal region includes approximately all of North and Central America in which the mean temperature of the hottest season does not exceed 18¡ C. (= 64. 4¡ F.). Its subdivisions are the Arctic zone and Boreal zone, the latter including the area between the Arctic and Transition zones.
2. Northern; pertaining to the north, or to the north wind; as, a boreal bird; a boreal blast.
- It blew him as a blade of grass is blown in a boreal blast; yet he sensed the pitch. - "Melomaniacs", James Huneker.
- Only the Great Spirit, who lives beyond the golden veils of the boreal lights, may hear the sobbing of a stricken human creature over the thing of which it has been bereft. - "The Eternal Maiden", T. Everett Harré.
- Out of the North the wild news came, Far flashing on its wings of flame, Swift as the boreal light that flies At midnight through the startled skies. - "Story Hour Readings: Seventh Year", E.C. Hartwell.