Important Idioms and Phrases starting with Alphabet- O
| S.No. | Idioms/Phrases | Meaning |
| 1. | Oily tongue | Flattering words |
| 2. | On one’s guard | Vigilant |
| 3. | On one’s last legs | Close to collapsing |
| 4. | Once for all | For the last time/ Conclusively |
| 5. | Open question | A question which may have more than one answer |