In medieval and Renaissance Spain, a Jew who had converted to Christianity. Under the relatively tolerant rule of the Muslim conquerors of Spain, a large Jewish community played an important part in Spanish life. This tolerance and prosperity continued for several centuries in regions reconquered by the Christians. During the 13th and 14th centuries, however, pressure from the clergy for conversion and incidents of persecution became more frequent. In 1391 a series of riots and massacres swept through the peninsula. Often, conversion was the price paid to stay alive. Pressure for conversion grew throughout the 15th century and achieved great success. Thousands of Jews became conversos, and they began to prosper within the Christian society, rising to high office in government service, education, medicine, business, and even the clergy. The most successful even married into the aristocracy. Yet the "old Christians" realized that many of those converted had changed religion only out of fear. While many conversos did become true converts to their new religion, some secretly continued to practice their ancestral faith.
Concern about backsliding conversos culminated in the founding of the Spanish Inquisition in 1478. Since experience suggested that the continued presence of Jews in the country encouraged conversos to relapse secretly, in 1492 the rulers ordered the expulsion of all unconverted Jews. Large numbers went into exile in Portugal and especially in Muslim North Africa, but the majority converted, either sincerely or out of fear. Despite (or probably because of) the success of many conversos in gaining wealth, political influence, and high office in church and state, Spanish society watched them closely. The Inquisition was the institution created to detect and punish those who relapsed into Jewish religious practices. During the 16th century, conversos suffered both covert and open discrimination, including exclusion from an increasing number of high offices in church and state and from the most prestigious colleges in the Spanish universities, the ones that controlled access to the highest offices in the country.
Historical Dictionary of Renaissance. Charles G. Nauert. 2004.