Wikipedia
New Christian (; ; ) was a law-effective and social category developed from the 15th century onwards, and used in what is today Spain and Portugal as well as their New World colonies, to refer to Sephardi Jews and Muslims (" Moors") who had converted to the Catholic Church, often by force or coercion. It was developed and employed after the Reconquista of the Iberian Peninsula by the Catholic Monarchs.
By law, the category of New Christian included not only recent converts, but also all their known baptized descendants with any fraction or quantum of New Christian blood up to the fourth generation, and then in Phillip II's reign it included any person with any fraction of New Christian blood "from time immemorial".
In Portugal, it was only in 1772 that Sebastião José de Carvalho e Melo, 1st Marquess of Pombal, finally decreed an end to the legal distinction between New Christians and Old Christians.