nos

dative of nosotros: to us, for us; accusative of nosotros: us; reflexive of nosotros: ourselves; each other; first person (except in vocative, and in the oblique it requires a preposition); I (singular; compare vos); first person nominative, prepositional and vocative plural pronoun

“A eso de las cuatro de la mañana todos nos dijimos buenas noches.” — Around four in the morning, we all told each other good night.

Inherited from Old Spanish nos, from accusative Latin nōs and dative Latin nōbīs, from Proto-Italic *nōs.