The Spanish language, or referring to the region of Castile in Spain.
From 'Castilla' (Castile), a region in central Spain. The name comes from Latin 'castellum' (castle/fortress), referring to the many castles of the region.
Castellano literally means 'of the castle-region,' and Castile was so dominant in Spain that its local language became THE Spanish language—a great example of how political power makes one dialect become 'the' official language.
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