In this article, we are going to analyze several categories of nouns that start with O. Nouns starting with O have amazing set of properties that need to be investigated. Before we do that, let’s discuss what nouns are and why they are so important.
A noun refers to individuals, things, ideas, and different items around us. Come to think of it, perhaps you could say that the difference between human language and the non-human ones – represented by the noises apes and monkeys make, is that we humans have nouns, and other animals don’t. In other words, noun is a word that names something.
Nouns are the first and focal building squares of language. There are a number of nouns that start with O that people use the most in their everyday lives and there are some that they seldom use.
Apart from that there are many nouns that start with O to describe people and what they do. Without any further ado, let’s go through the categories of nouns beginning with O, one by one.
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Table of Contents
Nouns That Start with O You Always Use
Nouns are everywhere in our speech and writing. They form a large proportion of English vocabulary and they come in a wide variety of types. Some of the nouns that start with O that we use regularly are given below.
1. Office
- Definition: a room, set of rooms, or building used as a place for commercial, professional, or bureaucratic work
- Synonyms: workplace, workroom
- Example: I don’t leave the office until eight o’clock last night.
2. Orange
- Definition: a round sweet fruit that has a thick orange skin and an orange center divided into many parts
- Synonyms: citrus-fruits, tangerine
- Example: Vitamin C is found in oranges and other citrus fruit.
3. Option
- Definition: one thing that can be chosen from a set of possibilities
- Synonyms: choice, preference, alternative
- Example: The best option would be to cancel the trip altogether.
4. Object
- Definition: a thing that you can see or touch but that is not usually a living animal, plant, or person
- Synonyms: thing, item, body
- Example: A new baby will automatically curl its fingers round any object it touches.
5. Observation
- Definition: the act of observing something or someone
- Synonyms: examination, consideration, investigation
- Example: The police are keeping the suspect under observation.
6. Oxygen
- Definition: a colorless, odorless reactive gas; the life-supporting component of the air
- Synonyms: gas, air, oxygenation
- Example: Oxygen is in high demand these days because of Covid-19.
7. Oil
- Definition: a viscous liquid derived from petroleum, especially for use as a fuel or lubricant
- Synonyms: lubricant, fuel, petrol
- Example: Oil does not mix with water.
8. Omelet
- Definition: a dish of beaten eggs cooked in a frying pan and served plain or with a savory or sweet topping or filling
- Synonyms: scrambled-egg, frittata
- Example: I’ll have an omelet with cheese on the side, please.
9. Outside
- Definition: the outer part or side of something
- Synonyms: exterior, surface
- Example: The outside of the house needs painting.
10. Onion
- Definition: a swollen edible bulb used as a vegetable, and composed of several concentric layers
- Synonyms: shallots, allium cepa,
- Example: Cook the onion in the oil until lightly colored.
Nouns That Start with O You Usually Use
Nouns can name things, although sometimes they might be hypothetical or imaginary things. Following is a list of nouns starting with O that we usually use in our daily life routine.
1. Origin
- Definition: the point or place where something begins, or arises
- Synonyms: beginning, start, origination
- Example: There are many theories about the origin of life.
2. Opinion
- Definition: a thought or belief about something or someone
- Synonyms: viewpoint, angle, judgement
- Example: What’s your opinion about this matter?
3. Oven
- Definition: an enclosed compartment, usually part of a cooker, for cooking and heating food
- Synonyms: stove, microwave, roaster
- Example: She completely forgot the cake in the oven.
4. Operation
- Definition: an act of surgery performed on a patient
- Synonyms: surgery, incision, resection
- Example: I’ve never felt better since my bypass operation.
5. Order
- Definition: a request to make, supply, or deliver food or goods
- Synonyms: command, request, instruction
- Example: “Can I take your order now?” said the waiter.
6. Outfit
- Definition: a set of clothes worn for a particular occasion or activity
- Synonyms: costume, uniform, suit
- Example: I’m going to wear my vampire outfit for Halloween.
7. Ornament
- Definition: a thing used or serving to make something look more attractive but usually having no practical purpose
- Synonyms: trinket, accessory, bibelot
- Example: They spent decades collecting these colorful ornaments.
8. Odor
- Definition: a particular smell, especially a bad one
- Synonyms: smell, aroma, stench
- Example: The odor she had smelled earlier hung in the air.
9. Organization
- Definition: a group of people who work together in an organized way for a shared purpose
- Synonyms: company, firm, corporation
- Example: The article was about the international aid organizations.
10. Oath
- Definition: a serious promise that you will tell the truth or that you will do what you have said
- Synonyms: pledge, vow, promise,
- Example: Presidents take an oath to uphold the Constitution.
Nouns That Start with O You Often Use
Following are some of the nouns beginning with O that we often make use of. Try and use these nouns that begin with the letter O into your own phrases and sentences.
1. Offer
- Definition: an expression of readiness to do or give something if desired
- Synonyms: proposal, suggestion, proposition
- Example: One day I’ll take you up on that offer.
2. Ounce
- Definition: a very small amount of something
- Synonyms: scrap, bit, iota
- Example: Robyn summoned up every ounce of strength.
3. Objection
- Definition: an expression or feeling of disapproval or opposition; a reason for disagreeing
- Synonyms: complaint, grievance, protestation
- Example: They have raised no objections to the latest plans.
4. Occasion
- Definition: a particular time, especially when something happens or has happened
- Synonyms: moment, event, circumstance
- Example: We met on several occasions to discuss the issue.
5. Obesity
- Definition: the condition of being very fat or overweight
- Synonyms: fatness, stoutness, corpulence
- Example: His obesity puts him at risk for major health problems.
6. Opening
- Definition: a space or gap that allows passage or access
- Synonyms: hole, aperture, gap
- Example: An opening in the roof would get rid of the smoke.
7. Omen
- Definition: something that is considered to be a sign of how a future event will take place
- Synonyms: sign, foreshadowing, symbol
- Example: Many people believe that a broken mirror is an omen of bad luck.
8. Obligation
- Definition: an act or course of action to which a person is morally or legally bound
- Synonyms: duty, commitment, responsibility
- Example: I have an obligation to look after her.
9. Obstacle
- Definition: a thing that blocks one’s way or prevents or hinders progress
- Synonyms: barrier, hurdle
- Example: The major obstacle to achieving that goal is money.
10. Obsession
- Definition: the state of being obsessed with someone or something
- Synonyms: fixation, compulsion, fascination
- Example: The kids have an obsession with computer games.
Nouns That Start with O You Sometimes Use
Every sentence must have a subject, and that subject will always be a noun. Following is a list of nouns beginning with O that we only use sometimes our everyday lives.
1. Offspring
- Definition: children or young of a particular parent or progenitor
- Synonyms: baby, kid, pup, children
- Example: Tom’s sister came over on Saturday with all her offspring.
2. Organ
- Definition: a part of the body of an animal or plant that performs a particular job
- Synonyms: unit, part, structure
- Example: He sustained injuries to his arms, legs and several internal organs.
3. Oration
- Definition: a formal public speech about a serious subject
- Synonyms: speech, address, lecture
- Example: He asked for no funeral oration.
4. Organism
- Definition: an individual animal, plant, or single-celled life form
- Synonyms: being, creature, animal
- Example: Amoebae and bacteria are single-celled organisms.
5. Oatmeal
- Definition: meal made from ground oats, used in porridge or oatcakes
- Synonyms: cereal, porridge
- Example: I switched back to oatmeal for four days.
6. Oppression
- Definition: the state of being subject to oppressive treatment
- Synonyms: persecution, abuse, maltreatment
- Example: Every human being has the right to freedom from oppression.
7. Orphanage
- Definition: a home for children whose parents are dead or unable to care for them
- Synonyms: asylum, shelter, foundation
- Example: He donated 1,000 dollars to an orphanage.
8. Oaf
- Definition: a man who is rough or clumsy and unintelligent
- Synonyms: clown, gawk, hulk
- Example: They are just big, clumsy oafs.
9. Omnibus
- Definition: a usually automotive public vehicle designed to carry a large number of passengers
- Synonyms: bus, vehicle, tram
- Example: In our neighborhood, most of the children ride an omnibus to school each day.
10. Onslaught
- Definition: a fierce or destructive attack
- Synonyms: charge, assault, attack
- Example: It is unlikely that his forces could withstand an enemy onslaught for very long.
Nouns That Start with O You Occasionally Use
Most of the nouns with letter O might be pretty commonly used, but there are some that are only used at some specific occasions. Following is a list of such nouns.
1. Obelisk
- Definition: a tapering stone pillar, typically having a square or rectangular cross section, set up as a monument or landmark
- Synonyms: pillar, monument, memorial
- Example: Each obelisk listed the members of an immortal household and their offspring.
2. Oligarchy
- Definition: government by a small group of powerful people
- Synonyms: authoritarianism, autocracy, totalitarianism
- Example: Their nation is an oligarchy.
3. Onyx
- Definition: a valuable stone that is used in jewelry, with white, black, grey, and other colored stripes
- Synonyms: stone, mineral, slab
- Example: Has my story of that pearl and onyx been lost on you?
4. Opus
- Definition: any work of art
- Synonyms: composition, work, piece
- Example: He showed us his latest opus, a truly magnificent painting of a vase of flowers.
5. Ordnance
- Definition: military supplies, especially weapons and bombs
- Synonyms: guns, cannon, artillery
- Example: The gun was a brand new piece of ordnance.
6. Osmosis
- Definition: a spontaneous diffusion of water or other solvents through a semipermeable membrane
- Synonyms: diffusion, infiltration
- Example: Fluid flows back into the tiny blood vessels by osmosis.
7. Ornithology
- Definition: the study of birds
- Synonyms: science, zoology, research
- Example: He found his vocation in ornithology.
8. Overalls
- Definition: a loose-fitting coat or one-piece garment worn over ordinary clothes for protection against dirt or heavy wear
- Synonyms: dungarees, outfit
- Example: She put on some overalls and got out a tin of paint.
9. Osteopathy
- Definition: the treatment of injuries to bones and muscles using pressure and movement
- Synonyms: ministration, surgery
- Example: Osteopathy involves massage and manipulation of the bones and joints.
10. Onomatopoeia
- Definition: the act of creating or using words that include sounds that are similar to the noises the words refer to
- Synonyms: echo, repetition, imitation
- Example: When asked to point out the onomatopoeia in the sentence describing a bird, I pointed to “chirp”.
Nouns That Start with O You Seldom Use
Nouns are indispensable because without them we would not be able to name anything in this world, especially noun words that start with O. For your convenience, we have shared some noun words starting with O below.
1. Obeisance
- Definition: a gesture expressing deferential respect, such as a bow or curtsy
- Synonyms: salutation, curtesy, bob
- Example: She made a deep obeisance.
2. Opprobrium
- Definition: harsh criticism or censure
- Synonyms: vituperation, criticism, censure
- Example: International opprobrium has been heaped on the country following its attack on its neighbors.
3. Oblation
- Definition: something that is offered as a religious sacrifice
- Synonyms: offering, sacrifice, libation
- Example: Incense was used for purification and as an oblation to ancestors.
4. Obliquity
- Definition: deviation from moral rectitude or sound thinking
- Synonyms: shift, transgression, turning
- Example: Barrow’s fade to winter blackness results from cosmic obliquity.
5. Obscurantism
- Definition: the practice of deliberately preventing the facts or full details of something from becoming known
- Synonyms: backsliding, backlash, withdrawal
- Example: Religious prejudice and scientific obscurantism have been closely entangled.
6. Offertory
- Definition: the offering of the bread and wine at the Eucharist
- Synonyms: offering, allowance, benefit
- Example: They donated the money to a collection which was brought up at the offertory.
7. Opulence
- Definition: the quality of being expensive and luxurious
- Synonyms: richness, luxury, splendor
- Example: He says living in such opulence makes him uneasy.
8. Orifice
- Definition: an opening or hole, especially one in the body, such as the mouth
- Synonyms: opening, hole, aperture
- Example: The driver was bleeding from every orifice.
9. Obloquy
- Definition: very strong public criticism or blame
- Synonyms: vilification, condemnation, denunciation
- Example: His controversial essays have brought him much obloquy.
10. Oubliette
- Definition: a secret dungeon with access only through a trapdoor in its ceiling.
- Synonyms: dungeon, jail, cell
- Example: Maria ends up in an oubliette where she reunites with her husband.
Positive Nouns That Start with O
There are some positive nouns that both carry and spread positivity wherever you use them. These are some of the positive nouns that start with O that one should have at one’s disposal.
1. Oasis
- Definition: a fertile spot in a desert, where water is found
- Synonyms: spring, wellspring
- Example: They stopped for the night at an oasis.
2. Objective
- Definition: something that you plan to do or achieve
- Synonyms: aim, intention, purpose
- Example: Her prime objective now is simply to stay in power.
3. Occupation
- Definition: a job or profession
- Synonyms: work, profession, job
- Example: Please fill in your name, age, and occupation.
4. Odyssey
- Definition: a long wandering or voyage usually marked by many changes of fortune
- Synonyms: adventure, expedition, exploration
- Example: They departed Texas on a three-year odyssey that took them as far as Japan
5. Obedience
- Definition: compliance with an order, request, or law or submission to another’s authority
- Synonyms: acquiescence, compliance
- Example: Obedience is the first duty of a soldier.
6. Opiate
- Definition: a drug that contains opium, especially one that causes sleep
- Synonyms: drug, narcotic, sedative
- Example: One woman suffered such severe pain she had to take opiates to control it.
7. Oomph
- Definition: the quality of being exciting, energetic, or sexually attractive
- Synonyms: fortitude, stamina, vigor
- Example: You need to put some oomph into your acting.
8. Opportunity
- Definition: a time or set of circumstances that makes it possible to do something
- Synonyms: chance, occasion, moment
- Example: Please contact us at the earliest opportunity.
9. Ovation
- Definition: a sustained and enthusiastic show of appreciation from an audience, especially by means of applause
- Synonyms: applause, clapping, cheering
- Example: Her performance received a thundering ovation.
10. Overture
- Definition: a piece of music that is an introduction to a longer piece, especially an opera
- Synonyms: opening, introduction, prelude
- Example: The programme opened with the overture to Wagner’s Flying Dutchman.
Nouns That Start with O to Describe a Person
Following are some of the nouns that start with O to describe a person, his actions and his profession. Try and memorize as many of these O nouns as possible.
1. Owner
- Definition: a person who owns something
- Synonyms: possessor, holder
- Example: He and his sister are the owners of the restaurant.
2. Officer
- Definition: a member of the police force
- Synonyms: agent, chief, deputy
- Example: Two officers responded to the call at 282 Main Street.
3. Operator
- Definition: someone who is skilled at dealing with people and getting what he or she wants from a situation
- Synonyms: machinist, worker, dealer, arranger
- Example: The tour operator will arrange transport and plan your itinerary.
4. Optimist
- Definition: a person who tends to be hopeful and confident about the future or the success of something
- Synonyms: dreamer, hoper, fantast
- Example: Only an eternal optimist could expect success.
5. Olympian
- Definition: a competitor in the Olympic Games
- Synonyms: sportsman, player
- Example: As the greatest Olympian, he is something of a sporting god.
6. Organizer
- Definition: a person who arranges an event or activity
- Synonyms: coordinator, arranger, facilitator
- Example: There aren’t enough seats for all the guests – I must tell the organizer.
7. Originator
- Definition: one who creates, founds or originates something
- Synonyms: architect, author, pioneer
- Example: He is best known as the originator of a long-running TV series.
8. Overseer
- Definition: one who directs, keeps watch over the work of others
- Synonyms: supervisor, executive, manager
- Example: The overseer was explaining the job to young trainees.
9. Optician
- Definition: a person qualified to prescribe and dispense glasses and contact lenses, and to detect eye diseases
- Synonyms: ophthalmologist, optometrist
- Example: Her youngest daughter is an optician.
10. Ogre
- Definition: a fierce and frightening person
- Synonyms: monster, bogeyman, devil
- Example: Some of my teachers were real ogres.
Nouns That Start with O – Full List (258 Words)
- Official
- Outfit
- Outburst
- Original
- Orb
- Organification
- Overpopulation
- Oxidation
- Octahedron
- Optimality
- Orphan
- Ochre
- Outrage
- Observance
- Outgrowth
- Occlusion
- Oversight
- Oxygen
- Orthicon
- Obscurity
- Outside
- Ocelot
- Opulence
- Outsider
- Octopus
- Oligarchy
- Opening
- Oak
- Ornithology
- Offshoot
- Ownership
- Overnight
- Objector
- Outbreak
- Ossification
- Orator
- Overture
- Occurrence
- Outpatient
- Orbit
- Obeisance
- Orifice
- Outfield
- Onlooker
- Orgone
- Oxen
- Ointment
- Ostracism
- Observer
- Oomph
- Outlaw
- Occasion
- Outflow
- Orderly
- Ocher
- Opposite
- Oiliness
- Origination
- Overalls
- Overcast
- Odyssey
- Oversimplification
- Outline
- Oratory
- Overestimation
- Ounce
- Outback
- Observation
- Outhouse
- Ordeal
- Onset
- Outcry
- Outlay
- Offender
- Outlawry
- Obverse
- Objectivity
- Oracle
- Oil
- Openness
- Otter
- Oblation
- Obelisk
- Ordnance
- Owner
- Outing
- Obstructionist
- Omnivore
- Ornamental
- Omen
- Occupancy
- Octagon
- Optician
- Omnibus
- Oilcloth
- Organizer
- Omelet
- Obligation
- Offal
- Orgasm
- Overthrow
- Ooze
- Owl
- Overtime
- Outcome
- Opera
- Orphanage
- Order
- Onion
- Oathe
- Opener
- Orchard
- Overpressure
- Overrun
- Oval
- Objective
- Obedience
- Objectification
- Overcoat
- Oubliette
- Ooh
- Outpost
- Offense
- Outlook
- Overflow
- Obesity
- Odor
- Oblong
- Outcast
- Organist
- Outset
- Overweight
- Output
- Operator
- Onomatopoeia
- Outfielder
- Obscurantism
- Oep
- Onrush
- Olive
- Overhead
- Officer
- Optimization
- Originality
- Optimism
- Ocarina
- Orchestra
- Opium
- October
- Oratorio
- Opiate
- Offer
- Opal
- Operetta
- Oscillation
- Obsidian
- Overhaul
- Ostrich
- Ocean
- Oiticica
- Object
- Ome
- Oppression
- Oxytetracycline
- Oasis
- Overlay
- Omnipotent
- Orthodontist
- Operand
- Omission
- Opportunity
- Obloquy
- Oblige
- Originator
- Operation
- Oscillator
- Overload
- Occupation
- Opprobrium
- Omnipotence
- Orthophosphate
- Organization
- Optimum
- Octoroon
- Offersey
- Oblivion
- Overhang
- Oven
- Option
- Overprotection
- Ovation
- Opinion
- Ornamentation
- Orthography
- Offertory
- Offering
- Ordinary
- Oral
- Obsession
- Osteopathy
- Open
- Oxide
- Obliteration
- Occupant
- Offspring
- Offing
- Orientation
- Ode
- Opus
- Onslaught
- Ogre
- Oneupmanship
- Organism
- Ornament
- Osmium
- Oatmeal
- Onyx
- Oilseed
- Orgy
- Oodles
- Organdy
- Overseer
- Orchestrator
- Ozone
- Optimist
- Oyster
- Obstacle
- Organ
- Oration
- Objection
- Officialdom
- Oath
- Office
- Ouster
- Olympian
- Outlet
- Oboist
- Opponent
- Opportunism
- Overpayment
- Oaf
- Ommission
- Opposition
- Osmosis
- Oceanography
- Orange
- Owi
- Overall
- Orchestration
- Oxalate
- Obscenity
- Oleomargarine
- Outreach
- Obliquity
- Origin
- Ordinance
- Oxcart
- Overexploitation
Final Thoughts on Nouns That Start with O
Thank you for going through this article on nouns starting with O. We hope that you would have found this article interesting. By now it is safe to say that the utilization of nouns to identify objects in our lives is endless, especially of nouns that start with O.
There are hundreds of nouns beginning with O that you might be completely unaware of, and this article is a great place to start if you want to read about them. Using such nouns in your everyday speech and writing will make you stand apart from everyone in terms of vocabulary and knowledge.
If you use these nouns that start with O in the company of your friends and colleagues, you will sound really cool. Therefore it is advised that you go through this article at least a couple of times.