Mameluco the word is believed to be of Arabic origin. The word in Arabic is Mamluk (masculine) or Mamluka (feminine) مملوك (masculine) or مملوكة (feminine). The word Mameluco is a term of Portuguese

Portuguese language

Portuguese is a Romance language that arose in the medieval Kingdom of Galicia, nowadays Galicia and Northern Portugal. The southern part of the Kingdom of Galicia became independent as the County of Portugal in 1095...

 origin describing the first generation offspring of a European and an Amerindian.
The corresponding Spanish word is mestizo

Mestizo

Mestizo is a term traditionally used in Latin America, Philippines and Spain for people of mixed European and Native American heritage or descent...

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In the 17th and 18th centuries, Mameluco was used to refer to organized bands of slave-hunters, also known as bandeirantes

Bandeirantes

The bandeirantes were composed of Indians , caboclos , and some whites who were the captains of the Bandeiras. Members of the 16th–18th century South American slave-hunting expeditions called bandeiras...

, who roamed the interior of South America from the Atlantic to the foothills of the Andes, and from Paraguay to the Orinoco river, invading Guarani-occupied areas in search of slaves.

The word may have become common in Portugal in the Middle Ages, deriving from the Arabic

Arabic language

Arabic is a name applied to the descendants of the Classical Arabic language of the 6th century AD, used most prominently in the Quran, the Islamic Holy Book...

 'mamlûk', used in the association with the Mamluk

Mamluk

A Mamluk was a soldier of slave origin, who were predominantly Cumans/Kipchaks The "mamluk phenomenon", as David Ayalon dubbed the creation of the specific warrior...

s.