Here is a list of nouns that start with AU.
auction, auctioneer, audacity, audience, audio
audit, audition, auditor, auditorium, aunt
aura, austerity, authentication, authenticator, authenticity
author, authoritarianism, authority, authorization, authorship
autism, auto, autobiography, autocollimator, autofluorescence
autograph, autoloader, automatic, automation, automaton
automobile, autonavigator, autonomy, autopsy, autosuggestibility
autumn, auxiliary
Hope you enjoy this page of nouns that start with au and the rest of this noun list a-z site as well.
Help make this a better resource by adding more nouns in the comments section. Thanks.