“Sole” is a noun and an adjective.
First, as an adjective. Some companies are the “sole importer” (importador exclusivo) of products.
Politicians in Spain have “sole rights” (derechos exclusivos) for certain things so all the citizens are not equal. “Sole” can also mean “only” (único).
Some people are “sole traders” (empresarios individuales) or “self-employed” (que trabaja por cuenta propia).
Shoes have soles (suelas), and mortals sometimes have sole (lenguado) for lunch.
So, sole for lunch this Easter?
