'araucanian' originates from Spanish, specifically the word 'Araucano' (from the region name 'Araucanía'), where 'Arauca-' referred to the people/region identified by Spanish colonists.

'araucanian' changed from Spanish 'Araucano' and the place-name 'Araucanía' and entered English in accounts of South America (19th century and earlier) as 'Araucanian' / 'araucanian', used as both noun and adjective.

Initially, it meant 'of or relating to the Araucan people or region' as used by Spanish colonists and later European writers; the core meaning has remained but modern usage prefers 'Mapuche' for the people and 'Araucanía' for the region.