OU or Ou or ou may stand for:
Outlook.com is a web-based suite of webmail, contacts, tasks, and calendaring services from Microsoft.
Outsourcing is an agreement in which one company hires another company to be responsible for a planned or existing activity that is or could be done internally,
Outlander is a drama television series based upon author Diana Gabaldon's historical time travel book series of the same name.
An outlaw motorcycle club, is a motorcycle subculture that has its roots in the immediate post-World War II era of North American society.
The Outer Hebrides (; Scottish Gaelic: Na h-Eileanan Siar [nə ˈhelanən ˈʃiəɾ] (listen) or Na h-Eileanan an Iar [nə ˈhelanən əˈɲiəɾ] (listen)), also known as the Western Isles, Innse Gall ("islands of the strangers") or the Long Isle/Long Island (Scottish Gaelic: An t-Eilean Fada), is an island chain off the west coast of mainland Scotland.
Outer space, or simply space, is the expanse that exists beyond the Earth and between celestial bodies.