late 14c., "predatory incursion," Scottish, from the verb (14c.), perhaps a back-formation of Middle English forreyer "raider, forager" (mid-14c.), from Old French forrier, from forrer "to forage," from forrage "fodder; foraging; pillaging, looting" (see forage (n.)). Disused by 18c.; revived by Scott. As a verb from 14c.