Index - O
| odd | Relude.Base, Relude |
| on | Relude.Function, Relude |
| OnDecodeError | Relude.String.Reexport, Relude.String, Relude |
| One | Relude.Container.One, Relude.Container, Relude |
| one | Relude.Container.One, Relude.Container, Relude |
| OneItem | Relude.Container.One, Relude.Container, Relude |
| OnError | Relude.String.Reexport, Relude.String, Relude |
| openFile | Relude.Lifted.File, Relude.Lifted, Relude |
| Option | |
| 1 (Data Constructor) | Relude.Monoid, Relude |
| 2 (Type/Class) | Relude.Monoid, Relude |
| optional | Relude.Applicative, Relude |
| or | Relude.Foldable.Reexport, Relude.Foldable, Relude |
| Ord | Relude.Base, Relude |
| ord | Relude.Base, Relude |
| Ordering | Relude.Base, Relude |
| ordNub | Relude.Nub, Relude |
| orM | Relude.Foldable.Fold, Relude.Foldable, Relude |
| otherwise | Relude.Bool.Reexport, Relude.Bool, Relude |
| ownName | Relude.Extra.CallStack |