- 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
- Off-center Adj Adv Verb
- Off-put Past Participle Verb
- Offend Verb
- Offer Noun Verb Adj
- Offer up Verb
- Office Noun Adj Verb
- Officer Noun Adj Verb
- Officialise Verb
- Officialize Verb
- Officiate Verb
- Offlap Noun Verb Adj
- Offline Adj Adv Noun Verb
- Offload Verb Noun
- Offprint Noun Verb Adj
- Offsaddle Verb Noun
- Offset Noun Verb Adj
- Offshore Adj Adv Noun Verb Past Participle
- Ogle Verb Noun Pres. Participle
- Oil Noun Verb Adj
- Oink Inter Noun Verb
- OK Adj Adv Inter Noun Verb Pnoun
- Okay Adj Adv Inter Noun Verb
- Olden Adj Verb
- Oleate Noun Verb Adj
- Oleograph Noun Adj Verb
- Omen Noun Verb
- Omit Verb
- Onboard Adj Verb Adv
- Onceover Noun Verb
- One-up Verb Adj Noun
- Onlap Noun Verb
- Oof Inter Noun Verb
- Ooh Inter Verb Noun
- Oomph Noun Inter Verb
- Oophorectomise Verb
- Oops Inter Noun Adj Verb
- Ooze Noun Verb Adj
- Ooze out Verb