OU or Ou or ou may stand for:
Outlook.com is a web-based suite of webmail, contacts, tasks, and calendaring services from Microsoft.
In business, outsourcing is an agreement in which one company contracts its own internal activity to a different company.
An outlaw motorcycle club is a motorcycle subculture that has its roots in the immediate post-World War II era of American society.
The Outer Hebrides (), also known as the Western Isles (Scottish Gaelic: Na h-Eileanan Siar [nə ˈhelanən ˈʃiəɾ] or Na h-Eileanan an Iar [nəˈhelanən əˈɲiəɾ]), Innse Gall ("islands of the strangers") or the Long Isle or the Long Island (Scottish Gaelic: An t-Eilean Fada), is an island chain off the west coast of mainland Scotland.
Outlander is a television drama series based on the historical time travel Outlander series of novels by Diana Gabaldon.