Old English us (cognate with Old Saxon, Old Frisian us, Old Norse, Swedish oss, Dutch ons, German uns), accusative and dative plural of we, from PIE *nes- (2), forming oblique cases of the first person plural personal pronoun (source also of Sanskrit nas, Avestan na, Hittite nash "us;" Greek no "we two;" Latin nos "we, us;" Old Church Slavonic ny "us," nasu "our;" Old Irish ni, Welsh ni "we, us"). The -n- is preserved in Germanic in Dutch ons, German uns.
also U.S., abbreviation of United States, attested from 1834. U.S.A. for "United States of America" is recorded from 1885; before that it generally meant "U.S. Army."