| # | Word | Igbo Meaning | English Meaning |
| 41 | Oak | Osisi akwụkwọ ya na-agbụcha agbụcha site n'afọ ruo n'afọ. | Decidous forest tree |
| 42 | Oasis | Ala na-emeta nri dị nọzara. | Fertile spot in desert. |
| 43 | Oat | ụ mkpụrụ osisi. | Grain of cereal plant. |
| 44 | Oath | Ịṅụ iyi. | Confirmation of truth of statement by naming of something sacred |
| 45 | Obdurate | Adịghị erube isi. | Stubborn, unyielding. |
| 46 | Obedience | Ịkpọ isi ala; nrube isi | A bow |
| 47 | Obese | Buru oke ibu. | Very fat |
| 48 | Obey | Rube isi. | Do as ordered |
| 49 | Obfuscate | Teji oji, gbaji. | Darken |
| 50 | Obiter | Na mberede | Accidentally |
| 51 | Obituary | Ọkwa ọnwụ | Notice of death |
| 52 | Object | Ihe. | Material thing |
| 53 | Objection | Gbagha. | State in opposition |
| 54 | Objective | Ebu m n'uche. | Thing or place aimed at |
| 55 | Objure | Ba mba | Reprove; scold |
| 56 | Oblation | Onyinye | Offering |
| 57 | Oblige | Aghaghị ime n'ihe mmụọ ma ọ bụ iwu. | Bind morally or legally to do service to. |
| 58 | Oblique | Akwụghị ọtọ. | Slanting |
| 59 | Obliterate | Hichapụ | Blot out |
| 60 | Oblivion | Ichefu | Forgetting or being forgotten |
Igbo Language & Culture