| Acronym | Definition |
|---|
| OO➣Object Oriented (Programming) |
| OO➣OpenOffice |
| OO➣Olive Oil |
| OO➣Peroxide (functional group) |
| OO➣On Order |
| OO➣Over and Out |
| OO➣Ozzy Osbourne |
| OO➣Oval Office |
| OO➣Owner Operator (trucking industry; also seen as O/O) |
| OO➣Operations Officer |
| OO➣Owner-Occupied (real estate) |
| OO➣Sky West Airlines |
| OO➣Official Observer (amateur radio) |
| OO➣Optimum Online |
| OO➣Original Oratory |
| OO➣Officers Only |
| OO➣Ombudsman's Office |
| OO➣Osteoid Osteoma |
| OO➣Obiettivi Operativi |
| OO➣Ordering Officer |
| OO➣Operator Office (trunks) |
| OO➣Ophthalmic Optician |
| OO➣Old Oakhamian |
| OO➣Optimistic Orators (Toastmasters Club) |
| OO➣Onderling Onafhankelijk (Dutch) |