- Obey
- Object
- Oblige
- Obscure
- Observe
- Obstruct
- Obtain
- Occupy
- Occur
- Offend
- Offer
- Officiate
- Ok
- Omit
- Open
- Operate
- Oppose
- Oppress
- Opt
- Optimize
- Orbit
- Orchestrate
- Ordain
- Order
- Organize
- Orientate
- Ornament
- Oscillate
- Ossify
- Ostracize
- Outline
- Outnumber
- Outperform
- Outplay
- Overact
- Overbalance
- Overbook
- Overcharge
- Overcompensate
- Overcook
- Overdose
- Overlook
- Overpower
- Overproduce
- Overreact
- Overwork
- Oxidize
- Oxygenate
