(1451–1504), queen of Castile 1474–1504 and of Aragon 1479–1504. Her marriage in 1469 to Ferdinand of Aragon helped to join together the Christian kingdoms of Castile and Aragon, marking the beginning of the unification of Spain. They instituted the Spanish Inquisition (1478) and supported Columbus's famous expedition of 1492.
Definition of Isabella I in US English:
Isabella I
proper noun
(1451–1504), queen of Castile 1474–1504 and of Aragon 1479–1504. Her marriage in 1469 to Ferdinand of Aragon marked the beginning of the unification of Spain. They instituted the Spanish Inquisition in 1478 and supported the explorations of Christopher Columbus in 1492.