- OK Adj Adv Inter Noun Verb
- Okay Adj Adv Inter Noun Verb
- Omit Verb
- Onboard Adj Verb
- One-up Verb
- Onlap Noun Verb
- Ooh Inter Verb
- Oophorectomise Verb
- Ooze Noun Verb
- Ooze out Verb
- Opacify Verb
- Opalesce Verb
- Open along Verb
- Open around Verb
- Open back Verb
- Open down Verb
- Open in Verb
- Open off Verb
- Open on Verb
- Open out Verb
- Open over Verb
- Open up Verb
- Operate Verb
- Operate along Verb
- Operate around Verb
- Operate in Verb
- Operate off Verb
- Operate on Verb
- Operate over Verb
- Operate under Verb
- Operationalise Verb
- Operationalize Verb
- Opiate Adj Noun Verb
- Opine Verb
- Oppose Verb
- Oppress Verb
- Oppugn Verb
- Opsonize Verb
- Opt Verb
- Opt in Verb
- Opt out Verb
- Optate Verb
- Optimise Verb
- Optimize Verb
- Orate Verb
- Orb Noun Verb
- Orbit Noun Verb
- Orchestrate Verb
- Ordain Verb
- Order Noun Verb
- Ordinate Adj Noun Verb
- Organise Verb
- Organize Verb
- Organize around Verb
- Orgasm Noun Verb
- Orient Noun Verb
- Orientalise Verb
- Orientalize Verb
- Orientate Verb
- Orienteer Noun Verb