| OK | All Correct 
| Others |
| OK | Czech Airlines
| Others |
| OK | Oakland Kids
| Others |
| OK | Obey of Kindness
| Others |
| OK | Object Kill
| Others |
| OK | Objection Killed
| Others |
| OK | Objection Killer
| Others |
| OK | Octopus Kicking
| Others |
| OK | Odnoklassniki
| Others |
| OK | of Knowledge
| Others |
| OK | Off to Kinderhook
| Others |
| OK | Official Knowledge
| Others |
| OK | Oh Koala
| Others |
| OK | Ohio and Kentucky
| Others |
| OK | Okay (Oll Korrect)
| Others |
| OK | Okay Kitty
| Others |
| OK | Okidoki
| Others |
| OK | Oklahoma
| State |
| OK | Ol Korrect
| Others |
| OK | Ola Kala
| Others |
| OK | Ola Kala (all is alright)
| Others |
| OK | Old Kentucky
| Others |
| OK | Old Keokuk
| Others |
| OK | Old Kinderhook
| Others |
| OK | Old Kingdom
| Others |
| OK | Older Kids
| Others |
| OK | Oll Korrect
| Others |
| OK | Oll Korrect or Olla Kalla
| Others |
| OK | Oll Korrekt
| Others |
| OK | Olla Kalla
| Others |
| OK | Olla Kalla or Oll Korrect or All Correct
| Others |
| OK | Olympia Kiwanis
| Others |
| OK | One Kiss
| Others |
| OK | Operation Klar
| Others |
| OK | Opportunity Knocking
| Others |
| OK | Opportunity Knocks
| Others |
| OK | Orange Kitten
| Others |
| OK | Organizational Knowledge
| Others |
| OK | Organized Knowledge
| Others |
| OK | Original Kaos
| Others |
| OK | Ornary Kitten
| Others |
| OK | Orrin Kendall
| Others |
| OK | Orrins Kendall
| Others |
| OK | OrtsKommandantur (Local Commandant)
| Others |
| OK | Orville Knoxville
| Others |
| OK | Other Kitty
| Others |
| OK | Our Kids
| Others |
| OK | Zero Kills
| Others |