O

English words starting with letter “o” with Greek origin:

1. Octagon – From ‘okto’ (eight) and ‘gonia’ (angle).
2. Odometer – From “hodos” (road) and metro (measure)
3. Odyssey – From ‘Odysseia’, the epic by Homer.
4. Oleander – From Greek ‘nerion’, but influenced by ‘olea’ (oil) due to resemblance.
5. Oligarchy – From ‘oligos’ (few) and ‘archein’ (to rule).
6. Oligocene – From ‘oligos’ and ‘kainos’ (new, recent).
7. Oligodendrocyte – From ‘oligos’, ‘dendron’ (tree), and ‘kytos’ (cell).
8. Oligophrenia – From ‘oligos’ and ‘phren’ (mind).
9. Oligopoly – From ‘oligos’ and ‘polein’ (to sell).
10. Oligosaccharide – From ‘oligos’ and ‘saccharon’ (sugar).
11. Oliguria – From ‘oligos’ (few, scanty) and ‘ouron’ (urine).
12. Omnipotent – From ‘omnis’ (all) and ‘potens’ (powerful), influenced by Greek.
13. Omniscient – From ‘omnis’ (all) and ‘scire’ (to know), influenced by Greek.
14. Oncology – From ‘onkos’ (tumor, bulk) and ‘logos’.
15. Onomatopoeia – From ‘onoma” name, poio (create)
16. Ontology – From ‘on’ (being) and ‘logos’.
17. Oogenesis – From ‘oion’ (egg) and ‘genesis’ (origin).
18. Oophorectomy – From ‘oophoron’ (ovary) and ‘ektome’ (cutting out).
19. Ootheca – From ootheke (ovary)
20. Ophthalmic – From ‘ophthalmos’.
21. Ophthalmology – From ‘ophthalmos’ (eye) and ‘logos’ (study).
22. Ophthalmoscope – From ‘ophthalmos’ and ‘skopein’ (to look at).
23. Optic – From Greek ‘optikos’ (of sight).
24. Orchestra – From ‘orchestra’, the circular part of the ancient Greek theatre.
25. Organ – From organo (organ)
26. Organic – From ‘organikos’ (of or pertaining to an organ).
27. Organisation – from ‘organo’ (organ)
28. Organism – From ‘organ’ (organ
29. Ornithology – From ‘ornithos’ (bird) and ‘logos’.
30. Orphan – From orfanos
31. Orphic – Pertaining to Orpheus, a mythical poet and musician.
32. Orthodontics – From ‘orthos’ and ‘odous’ (tooth).
33. Orthodox – From ‘orthos’ (straight, correct) and ‘doxa’ (opinion).
34. Orthography – From ‘orthos’ and ‘graphein’ (to write).
35. Orthopaedic – From ‘orthos’ and ‘pais’ (child).
36. Oscilloscope – From ‘oskillo’ (to swing) and ‘skopein’.
37. Osmium – From ‘osme’ (smell).
38. Osmosis – From Greek ‘osmos’ (a push).
39. Osteopathy – From ‘osteon’ and ‘pathos’ (suffering).
40. Osteoporosis – From ‘osteon’ (bone) and ‘poros’ (passage, pore).
41. Otorhinolaryngologist – From oto (ear), rhino (nose), laryngas (throat), logist (scholar)
42. Oxidize – From ‘oxy’ and ‘-ize’, pertaining to combining with oxygen.
43. Oxygen – From Greek ‘oxy’ (sharp, acid) and ‘genes’ (producer).
44. Oxymoron – From ‘oxy’ (sharp) and ‘moros’ (dull, foolish).
45. Oxytocin – From ‘oxy’ and ‘tokos’ (birth).
46. Ozone – From ‘ozon’, meaning smelling.