| OIDIOID | • oidioid adj. Of or relating to the fungus genus Oidium. • OIDIOID adj. relating to an oidium. |
| OIKISTS | • oikists n. Plural of oikist. • OIKIST n. (historical) the founder of a colony, also OECIST. |
| OILBIRD | • oilbird n. Steatornis caripensis, a nocturnal South American bird related to the nightjars that feeds on the fruit… • OILBIRD n. a nocturnal bird of South America and Trinidad, aka guacharo. |
| OILCAMP | • OILCAMP n. a living area for workers at an oil well. |
| OILCANS | • oilcans n. Plural of oilcan. • OILCAN n. a can containing oil. |
| OILCUPS | • oilcups n. Plural of oilcup. • OILCUP n. a closed cup for supplying lubricant. |
| OILHOLE | • OILHOLE n. a hole through which oil is injected. |
| OILIEST | • oiliest adj. Superlative form of oily: most oily. • OILY adj. covered in oil. |
| OILLETS | • oillets n. Plural of oillet. • OILLET n. (obsolete) an eyelet. |
| OILNUTS | • oilnuts n. Plural of oilnut. • OILNUT n. a North American butternut. |
| OILPANS | • oilpans n. Plural of oilpan. • oil␣pans n. Plural of oil pan. • OILPAN n. (US) a sump. |
| OILSEED | • oilseed n. The seed of any of several plants which are used commercially as a source of vegetable oil. • oilseed n. The plant that yields such seed. • OILSEED n. a kind of rape, the seeds of which contain oil. |
| OILSKIN | • oilskin n. Cloth made from cotton and treated with oil and pigment to make it waterproof. • oilskin n. A raincoat made from cotton fabric treated with oil and pigment to make it waterproof. • oilskin n. (By extension) Foul-weather gear worn by sailors, whether of natural or synthetic materials. |
| OILWAYS | • oilways n. Plural of oilway. • OILWAY n. a channel for the passage of oil. |
| OINKING | • oinking v. Present participle of oink. • OINK v. to grunt like a hog. |
| OINOMEL | • oinomel n. Alternative form of oenomel. • OINOMEL n. (Greek) a beverage of ancient Greece consisting of wine and honey, also OENOMEL. |
| OINTING | • ointing v. Present participle of oint. • OINT v. (Dryden) to anoint. |