An Etymological Dictionary of the German Language/Annotated/aus

by Friedrich Kluge

aus, adverb and preposition, ‘out, forth, from, by reason of,’ from the equivalent Middle High German and Old High German ûȥ, adverb, preposition; corresponds to Gothic ût, adverb, ‘out (thither, hence),’ Anglo-Saxon ût, ‘out (thither, hence), out of doors, outside,’ English out, Dutch uit, preposition, adverb, ‘out,’ Old Saxon ût. Compare außen, außer. The common Teutonic ût (from ût-a?) is based upon Aryan ûd (ŭd); compare Sanscrit ud, a verbal particle, ‘out, out (thither), aloft, upwards.’