Here is a comprehensive list of words that begin with the letter O, each followed by a brief description.
Oaf
A clumsy or unintelligent person.
Oar
A tool used to row or steer a boat, typically made of wood or metal.
Oasis
A fertile area in a desert where water is available.
Obdurate
Stubbornly refusing to change one's opinion or course of action.
Obey
To follow commands or instructions.
Object
A material thing that can be seen and touched or an aim or goal.
Oblivious
Unaware or unconscious of what is happening around one.
Obnoxious
Highly offensive or unpleasant.
Observant
Quick to notice or perceive things.
Obstruct
To block or prevent movement or progress.
Obtain
To acquire or get something.
Obvious
Easily perceived or understood; clear.
Occasion
A particular time or instance of an event.
Occupy
To take up space or be present in a place.
Ocean
A large body of saltwater that covers most of the Earth's surface.
Octagon
A polygon with eight sides and eight angles.
Ode
A lyrical poem, often addressed to a particular person or thing.
Odor
A distinctive smell.
Offend
To cause someone to feel upset, annoyed, or resentful.
Office
A room or building where people work, usually in a professional setting.
Officer
A person holding a position of authority, especially in the military or police.
Often
Frequently; many times.
Omit
To leave out or exclude something.
Onyx
A type of quartz that is typically black and white or various colors.
Opera
A dramatic work in one or more acts, set to music for singers and instrumentalists.
Opine
To express an opinion.
Opt
To make a choice or decision from among options.
Option
A choice or alternative.
Orchard
A piece of land dedicated to growing fruit trees.
Organ
A musical instrument with a keyboard and pipes or a vital part of the body that performs a specific function.
Originate
To begin or start.
Ornament
An object used to decorate or embellish something.
Other
Referring to someone or something different or additional.
Outline
A general description or plan giving the essential features of something.
Output
The amount of something produced by a person, machine, or system.
Overcome
To succeed in dealing with a problem or difficulty.
Overlap
To extend over or cover part of something else.
Overt
Done or shown openly; not secret.
Overwhelm
To overpower or affect deeply.
Owl
A nocturnal bird known for its distinctive hooting sound and keen eyesight.