us (pron.) Look up us at Dictionary.com
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 (cognates: 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.
US Look up US at Dictionary.com
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."