IRUN, a frontier town of Spain, in the province of Guipùzcoa, on the left bank of the Bidassoa, opposite the French village of Hendaye. It is the northern terminus of the Spanish Northern Railway. It has a fine Renaissance church, that of Nuestra Senora del Juncal; and its industries (iron-works, tanyards, potteries) are in a flourishing condition. The population in 1877 was 7040.