- O.D. Noun Verb
- O.K. Adj Adv Inter Noun Verb
- Oak Noun Adj Verb
- Oar Noun Verb Adj
- Oast Noun Verb Adj
- Oath Noun Inter Adj Verb
- Obduce Verb
- Obduct Verb Past Participle Pres. Participle
- Obdurate Adj Verb
- Obeah Noun Verb
- Obelise Verb
- Obelize Verb
- Obey Verb
- Obfuscate Verb Pres. Participle Past Participle
- Object Noun Verb Adj
- Objectified Past Participle Verb
- Objectify Verb Pres. Participle Past Participle
- Objurgate Verb
- Obligate Adj Verb
- Oblige Verb Past Participle Pres. Participle
- Oblique Adj Noun Adv Verb
- Obliterate Verb Adj Past Participle Pres. Participle
- Obnubilate Verb
- Obrogate Verb
- Obscure Adj Verb
- Obscured Past Participle Verb
- Observe Verb
- Obsess Verb
- Obsess over Verb
- Obsolete Adj Verb
- Obstinate Adj Verb
- Obstruct Verb
- Obtain Verb
- Obtemper Verb
- Obtest Verb
- Obtrude Verb
- Obtund Verb Past Participle
- Obturate Verb
- Obvert Verb
- Obviate Verb
- Occasion Noun Verb Adj
- Occidentalise Verb
- Occidentalised Past Participle Verb
- Occlude Verb Past Participle Pres. Participle
- Occult Adj Noun Verb
- Occupied Adj Verb
- Occupy Verb
- Occur Verb
- Occur along Verb
- Occur around Verb
- Occur on Verb
- Occur over Verb
- Ocellate Adj Verb
- Ocher Noun Adj Verb
- Ochre Adj Noun Verb
- OCR Noun Verb Adj
- Octroy Noun Verb
- Octuple Adj Noun Verb
- Octuplicate Adj Noun Verb
- Odorize Verb