| Abbreviation | Definition |
|---|---|
| OMGITIBAN | Oh My Gosh I Think I Broke A Nail |
| OMGM | Oh My God Mom |
| OMGYKK | Oh My God, You Killed Kenny! |
| OMI | Oh My Irene |
| OMKS | On My Kid is Short |
| OMKS | Open Minded Kinetic Souls |
| OMLG | Oh My Lord Ganesha |
| OMP | Oh My Panda |
| OMPA | Our Most Popular Acronyms |
| OMR | Oh My Ra |
| ONC | Only Non-Canadians |
| ONDCP | Official National Department of Cultural Purity |
| ONLINE | Oxygen Nail Love Ice Now Extra |
| ONY | Original Noodle For You |
| ONYHTREDY | Oh No! You Have To Ruin Everything, Don't You!?! |
| OO | Ohh Ohh |
| OOB | Ohayo, Ohayo, Bonjour |
| OOBE | Out Of Buggy Experience |
| OOC | Out Of Carpet |
| OOK | Object-Oriented Khaos |