| Oath |
A person promises to tell the truth in court |
| Obituary |
A news article that reports the recent death of a person |
| Occidental |
That which falls on the western countries |
| Ochlocracy |
Government by the populace |
| Odontology |
The scientific study of the structure and diseases of teeth |
| Oligarchy |
A small group of people having control of a country or organization |
| Oligocracy |
Government by small fraction or group of families |
| Omnibus |
Book containing all the published work of an author |
| Omnipotent, Omnipotence |
Having complete power |
| Oneirophile |
A person who loves dream |
| Ophiophobia |
Fear of snakes |
| Oracity |
An ability to express oneself in speech |
| Orchard |
A piece of enclosed land planted with fruit trees |
| Ornithology |
Study of birds |
| Orthopaedics |
The study of the structure of bones and curvature of the spine |
| Otiose |
Having to a useful purpose |
