Irún (ērōnˈ) [key], town (1990 pop. 55,200), Guipúzcoa prov., N Spain, in the Basque region near the French border, on the Bidassoa River near the Bay of Biscay. It is a commercial and manufacturing center producing paper and leather goods. Lead and iron mines are nearby. Irún was staunchly defended by the Loyalists in the civil war of 1936–1939.