AU simply means alternate universe in fan fiction forums. You take a famous person and make them unfamous, make them "normal."

A fanfiction term meaning Alternate Universe.

An AU fic is a fanfic which includes elements of a book which are completely unfeasible.

"AU" - the symbol for gold on the Periodical Table of Elements

The astronomical unit (AU or au or a.u. or rarely ua) is a unit of distance, approximately equal to the mean distance between Earth and Sun. The currently accepted value of the AU is 149,597,870,691 ± 30 metres (about 150 million kilometres or 93 million miles).

Abbreviation for American University, A school of highly affluent, overly intellectual, and often-times pretentious students. It is not uncommon to be sitting in an AU classroom and have a prince, the daughter of a Fortune 500 CEO, and an ambassador's son within a 4-foot radius.

'Au' is also a Finnish word and it means the same as 'ouch' in English.

a sound made by those of island decent