Of or pertaining to an island; surrounded by water: opposed to continental.Hemmed in like an island; standing alone; surrounded by what is different or incongruous: as, an insular eminence in a plain.Of or pertaining to the inhabitants of an island; characteristic of insulated or isolated persons; hence, narrow; contracted: as, insular prejudices.In entomology, situated alone: applied to galls which occur singly on a leaf.In anatomy, of or pertaining to the insula of the brain, or island of Reil.n. One who dwells in an island; an islander.