The Spanish word for underwear is
ropa interior

Pronunciation

Click the button to hear the pronunication of ropa interior

The gender of ropa interior is feminine. E.g. la ropa interior.

¿Dónde está su sección de ropa interior?	Where is your underwear section?
Él está caminando por ahí en ropa interior.	He's walking around in his underwear.
Cámbiate de ropa interior todos los días.	Change underwear daily.
No llevaba nada puesto excepto su ropa interior.	He was wearing nothing but his underwear.