(medieval Spain and Portugal) a disparaging term for a Jew who converted to Christianity in order to avoid persecution but continued to practice their religion secretly WordNet 3.0 & Open English WordNet

Marranos is one of the terms used in relation to Spanish and Portuguese Jews who converted or were forced by the Spanish and Portuguese crowns to convert to Christianity during the fifteenth and sixteenth centuries, but continued to practice Judaism in secrecy or were suspected of it, referred to as Crypto-Jews. Wikipedia

A Jew of the Iberian peninsula who maintained a private religious identity behind a façade of Catholicism Wikipedia Disambiguation

Jews forcibly converted to Catholicism in Spain Wikidata

Any of the Sephardi Jews who stayed in Iberia during the Spanish Inquisition, and continued to practice Judaism in secret. Wiktionary

Iberian Jew who practised Judaism in secret. Wiktionary (translation)