In Spanish slang, 'balneario' is not a slang term, but a standard Spanish word. It refers to a place equipped for bathing, swimming, and usually also for staying, often by the sea or a hot spring. It can also mean a public bathing or swimming facility.
Examples
- Spanish: Vamos a pasar el fin de semana en el balneario para relajarnos.
- English: We're going to spend the weekend at the spa to relax.