Letters and spelling

Words that start with the letter O

This list gathers common and slightly challenging words that begin with O, from everyday nouns to descriptive adjectives. Use it to build spelling confidence, expand vocabulary, or find a word for a word game or writing project.

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Words that start with the letter O

Word	Meaning	In a sentence
obeyverb	To do what one is told or required to do by a person, rule, or law.	Well-trained dogs learn to obey simple commands like sit and stay.
objectnoun	A physical thing that can be seen or touched but is not alive.	She placed a small glass object on the shelf beside her books.
obtainverb	To get something, often through effort or a request.	You can obtain a map from the visitor center.
occasionnoun	A particular time when something happens, or a special or noteworthy event.	We saved the good china for a special occasion like a wedding.
oceannoun	One of the huge bodies of salt water covering most of Earth's surface.	The ship sailed across the Atlantic Ocean for nearly two weeks.
octagonnoun	A two-dimensional shape with eight straight sides and eight angles.	A stop sign is shaped like a regular octagon with equal sides.
oddadjective	Unusual, strange, or different from what is normal or expected.	There was something odd about the way he avoided answering the question.
offerverb	To present something for someone to accept, reject, or consider.	The company offered her a promotion after her successful first year.
officenoun	A room or building where people work at desks, typically doing administrative tasks.	She arrived at the office early to prepare for the morning meeting.
oftenadverb	Frequently; on many occasions or at short intervals.	We often walk to the farmers market together on quiet Saturday mornings.
ointmentnoun	A smooth, greasy substance rubbed on the skin for healing or soothing purposes.	The doctor prescribed an ointment to soothe the itchy rash on his arm.
olivenoun	A small oval fruit with a bitter taste, eaten or pressed for its oil.	She added a handful of green olives to the fresh salad.
omitverb	To leave out or exclude someone or something, whether deliberately or by oversight.	The report omitted several key details that changed the overall conclusion.
onionnoun	A round vegetable bulb with a strong smell and taste, used widely in cooking.	Chopping the onion made her eyes water before she even started cooking.
opaqueadjective	Not letting light pass through, so that objects behind it cannot be seen.	The bathroom window used opaque glass to let in light while preserving privacy.
openadjective	Not shut or covered, allowing something to pass in or out.	An open window let the cool air into the room.
opinionnoun	A personal view, belief, or judgment about something that is not necessarily based on fact.	In my opinion, the new policy will do more harm than good.
opponentnoun	A person who competes against another in a contest, game, or argument.	She shook hands with her opponent after losing a close tennis match.
opportunitynoun	A favorable set of circumstances that makes it possible to do or achieve something.	Moving to the city gave her the opportunity to study at a better university.
opposeverb	To disagree with or actively resist a plan, idea, or person, often by arguing or fighting against it.	Several senators opposed the bill, arguing it would raise costs for small businesses.
optimistnoun	A person who tends to expect the best possible outcome in any situation.	As an optimist, he was sure the delayed flight would still arrive on time.
optionnoun	A thing that may be chosen from a set of possibilities available to someone.	Renting an apartment seemed like a safer option than buying a house right now.
orangenoun	A round citrus fruit with a thick skin and sweet, juicy segments inside.	She peeled an orange and shared the segments with her sister.
orbitnoun	The curved path that an object in space follows around a star, planet, or other larger body.	The satellite completes one orbit of Earth roughly every ninety minutes.
orchardnoun	A piece of land planted with fruit trees, often enclosed and carefully tended.	We picked baskets of apples from the orchard behind the farmhouse.
orchestranoun	A large group of musicians who together perform instrumental music, often with strings and winds.	The orchestra tuned their instruments before the conductor raised his baton.
ordinaryadjective	Normal or usual, without anything special, unusual, or noteworthy about it.	It was an ordinary Tuesday until the fire alarm went off during lunch.
organizeverb	To arrange things systematically, or to plan and coordinate an activity or event.	She organized her books alphabetically so she could find them quickly.
originnoun	The point or source from which something begins, derives, or first develops.	The origin of the word remains uncertain despite years of research.
ostrichnoun	A large flightless bird native to Africa, known for its long neck and fast running.	The ostrich sprinted across the savanna faster than any predator could follow.
outcomenoun	The way a situation, action, or process finally turns out; a result.	The outcome of the election surprised even the most experienced analysts.
outlinenoun	A general summary or plan that gives the main points of something without full detail.	She wrote an outline of the essay before drafting the full paragraphs.
outsidepreposition	Not within the limits, boundaries, or interior of a particular place, area, or category.	The dog waited patiently outside the grocery store while its owner shopped.
ovaladjective	Having a rounded, elongated shape resembling that of an egg.	She drew an oval face before adding the eyes and nose.
ovennoun	An enclosed compartment or appliance used for baking, roasting, or heating food.	She preheated the oven before sliding in the tray of cookies.
overcomeverb	To successfully deal with or gain control over a problem or difficulty.	She overcame her fear of public speaking after months of practice.
owlnoun	A nocturnal bird of prey with large eyes, a flat face, and a hooked beak.	An owl hooted softly from the branches of the old oak tree.
oxygennoun	A colorless, odorless gas in the air that humans and animals need to breathe in order to survive.	Firefighters carried extra tanks of oxygen so they could breathe safely inside the smoke-filled building.
oysternoun	A soft-bodied shellfish with a hinged shell that lives in the sea and is often eaten raw or cooked.	The chef shucked a dozen oysters and served them on ice with lemon wedges.

Frequently asked questions

What are some words that start with O?

Common examples include ocean, office, opinion, option, and orange, along with less common ones like octagon, ointment, and ostrich.