Index - O
| oldlace | Diagrams.Prelude |
| olive | Diagrams.Prelude |
| olivedrab | Diagrams.Prelude |
| open | Diagrams.Path, Diagrams.Prelude |
| Options | Diagrams.Prelude |
| orange | Diagrams.Prelude |
| orangered | Diagrams.Prelude |
| orchid | Diagrams.Prelude |
| OrderedField | Diagrams.Prelude |
| orientation | Diagrams.TwoD.Shapes, Diagrams.TwoD, Diagrams.Prelude |
| OrientToX | Diagrams.TwoD.Shapes, Diagrams.TwoD, Diagrams.Prelude |
| OrientToY | Diagrams.TwoD.Shapes, Diagrams.TwoD, Diagrams.Prelude |
| origin | Diagrams.Prelude |