Index - O
| occ | Twee.Base |
| occurs | Twee.Term, Twee.Base |
| occVar | Twee.Base |
| OneLineMode | Twee.Pretty, Twee.Base |
| optimise | Twee.Join |
| Or | Twee.Constraints |
| order | Twee.Equation |
| Ordered | Twee.Constraints, Twee.Base |
| orElse | Twee.Utils |
| orient | Twee.Rule |
| Orientation | Twee.Rule |
| orientation | Twee.Rule |
| Oriented | Twee.Rule |
| oriented | Twee.Rule |
| orientTerms | Twee.Constraints, Twee.Base |
| Output | |
| 1 (Type/Class) | Twee |
| 2 (Data Constructor) | Twee |
| output_message | Twee |
| Overlap | |
| 1 (Type/Class) | Twee.CP |
| 2 (Data Constructor) | Twee.CP |
| overlapAt | Twee.CP |
| OverlapOf | Twee.CP |
| overlapProof | Twee.CP |
| overlaps | Twee.CP |
| overlapsChurch | Twee.CP |
| overlap_depth | Twee.CP |
| overlap_eqn | Twee.CP |
| overlap_inner | Twee.CP |
| overlap_pos | Twee.CP |
| overlap_top | Twee.CP |