| Term | Full Form | Category |
|---|---|---|
| O | Contour Pattern | Others |
| O | form O solenoid | Others |
| O | Hug | Others |
| O | Oakland | Others |
| O | Oasis | Others |
| O | Oatmeal | Others |
| O | Obedience | Others |
| O | Obedient | Others |
| O | Oben | Others |
| O | Oberst | Others |
| O | Object | Others |
| O | Objectives | Others |
| O | Obliqueness | Others |
| O | Oblivion | Others |
| O | Observation | Others |
| O | Observed | Others |
| O | Obvious | Others |
| O | Occipito | Others |
| O | Occlude | Others |
| O | Occult | Others |
| O | Octant | Others |
| o | octet | Others |
| O | Octopus | Others |
| O | Odd | Others |
| O | Oddity | Others |
| O | Odds | Others |
| O | Odin | Others |
| O | Odor | Others |
| O | Of | Others |
| O | Off | Others |
| O | Offer | Others |
| O | Officer | Others |
| O | Official | Others |
| O | Offset | Others |
| O | Often | Others |
| O | Oh![]() | Slang |
| O | Ohm | Others |
| O | Ola | Others |
| O | Old | Others |
| O | Oldenburg | Others |
| O | Oldest | Others |
| O | Oliver | Others |
| O | Oluolu | Others |
| O | Olympics | Others |
| O | Omaha | Others |
| O | Omicron | Others |
| O | Omni | Others |
| O | Omologato | Others |
| O | One | Others |
| O | Ongoing | Others |