Marranos or 'secret Jews' were Sephardic Jews, or Jewish people living in the Iberian peninsula, forced to convert to Catholicism-Christianity or be expelled from the Kingdoms of Castile and Aragon (Spain). This designation officially began in 1492 with the Castilian Alhambra Decree, reversing protections in the Treaty of Granada (1491), and used for conversos, or ' confirmed converts', at first. However, soon Marranos was used for people that continued to practice Judaism secretly, crypto-Jews preserving their Jewish identity, 'the secret Jews' or judíos escondidos (in Hebrew Anusim).
Marrano in 15th century Spanish first meant pig, from the ritual prohibition against eating pork, practiced by both Jews and Muslims. During the Spanish Inquisition Marrano acquired the pejorative meanings: "filthy-pig" (sucio); swine (sin escrúpulos); and "filthy-dirty". In contemporary Spanish the word is no longer associated with Jews. In contemporary Portuguese the word refers only to crypto-Jews, with marrão meaning the animal pig or swine.
Not all conversos were accused of being Marranos. Those suspicions arose during times of social and political tension, when resentment targeted conversos who rose in position or influence. Catholic people who were jealous found it convenient to accuse them of secretly continuing Judaism as a way of attacking them in a society of state religion. Muslim conversos and crypto-Muslims were named Moriscos, also persecuted by the Inquisition.