UO

UO may stand for:

Arts and entertainment

 * Call of Duty: United Offensive, an expansion pack for the popular first-person shooter computer game, Call of Duty
 * Ultima Online, a graphical massively multiplayer online role-playing game
 * Underoath, an American Christian metalcore band from Tampa, Florida
 * Urge Overkill, an alternative rock band, formed in Chicago, United States

Businesses

 * Universal Orlando, a theme park resort in Orlando, Florida
 * Urban Outfitters, a publicly traded American company
 * Hong Kong Express Airways (IATA code: UO), an airline based in Hong Kong

Universities

 * University of Okara, a public university in Okara, Punjab, Pakistan
 * University of Oregon, a public research university in Eugene, Oregon, USA
 * University of Osnabrück, public university in Osnabrück, Lower Saxony, Germany
 * University of Otago, a public university in Dunedin, New Zealand
 * University of Oradea, a public university in Oradea, Romania
 * University of Ottawa, a public university in Canada
 * University of Oxford, a public university in United Kingdom

Other organizations

 * Orthodox Union, a kosher certification service which places a "U inside O" logo on food packaging

Other uses

 * Unexploded ordnance, explosive weapons that did not explode when they were employed
 * Urate oxidase, an enzyme that catalyzes the oxidation of uric acid to 5-hydroxyisourate