In Spanish slang, 'azul' is not a slang term, but a standard Spanish word that literally translates to 'blue'. However, depending on the context, it can also be used to describe a person who is sad or depressed.
Examples
- Spanish: Estoy un poco azul hoy, no me apetece salir a la calle.
- English: I'm feeling a bit blue today, I don't feel like going out.