The king of Castile and Aragon who ruled jointly with his wife Isabella; his marriage to Isabella I in 1469 marked the beginning of the modern state of Spain and their capture of Granada from the Moors in 1492 united Spain as one country; they instituted the Spanish Inquisition in 1478 and supported the expedition of Christopher Columbus in 1492 (1452-1516).

synonyms: Ferdinand, Ferdinand of Aragon, Ferdinand the Catholic, King Ferdinand.