AO 

Area of Operations. Army-speak.

When the General showed up at the barracks it was time to unass the AO.

AO by Parnelli Joneser May 7, 2005

AO 

..is short for ‘Adults Only’ (most extreme videogame rating in the U.S.). See also the other vg ratings: EC(Early Childhood), K-A(Kids to Adults; was replaced by 'E' in 1996), E(Everyone), E10+(Everyone ten years of age or older), T(Teen), M(Mature Audience), AO(Adults Only), and ESRB.

GTA:SA(Grand Theft Auto: San Andreas) is no longer rated 'M', but instead 'AO', and subsequesntly is no longer on the shelves, barely in stock at all.

AO by Victor Van Styn August 22, 2005

AO 

..is short for ‘Adults Only’ (most extreme videogame rating in the States). See also: EC, K-A, E, E10+, T, M, AO, and ESRB.

GTA:SA is no longer rated 'M', but instead 'AO', and subsequesntly is no longer on the shelves, barely in stock at all.

AO by Victor Van Styn August 22, 2005

AO 

Armpit odour.
Also known as PO. Similar to BO but somebody with AO reeks very strongly of funky pits.

Piss you!!! That dude that just went past has a terrible case of AO!!! :-(

AO by Telephony July 25, 2020

AO 

Short for Anal Only

My girlfriend and I do AO

AO by Minx137 August 9, 2017

AO 

Arresting Officer

"How was getting arrested this time?"
"Not too bad, had a nice AO for once."

AO by LazySmurf November 28, 2014

ao 

MMORPG Anarchy Online

ao by stevo July 3, 2003