- Opacify Verb Past Participle
- Opalesce Verb
- Opaque Adj Noun Verb
- Ope Inter Verb Past Participle
- Open Adj Noun Verb Adv
- 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
- Opencast Adj Noun 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
- Ophthalmoscope Noun Verb
- Opiate Adj Noun Verb
- Opine Verb
- Opportune Adj Verb
- Oppose Verb Pres. Participle Past Participle Noun
- Oppress Verb
- Oppugn Verb Past Participle Pres. Participle
- Opsonize Verb
- Opt Verb
- Opt in Verb
- Opt out Verb
- Optate Verb
- Optimise Verb
- Optimize Verb
- Option Noun Verb Adj
- Oracle Noun Verb Pnoun Adj
- Orange Adj Noun Verb
- Orate Verb
- Orb Noun Verb Adj
- Orbit Noun Verb Adj Pres. Participle Past Participle
- Orchestrate Verb Past Participle Pres. Participle
- Ordain Verb
- Ordeal Noun Verb
- Order Noun Verb Adj Past Participle
- Ordinate Adj Noun Verb
- Organise Verb
- Organize Verb
- Organize around Verb
- Organized Adj Past Participle Verb
- Orgasm Noun Verb Adj
- Orient Noun Verb Adj Pnoun
- Orientalise Verb
- Orientalize Verb
- Orientate Verb Past Participle Pres. Participle