Nouns That Start With O

262 words Words by letter Checked 9 Oct 2026

These nouns that start with O come from a standard English dictionary used for word games, ranked by how often each word is used in everyday writing. There are 262 nouns starting with O on this page. The 100 most common come first, each with a short meaning, followed by shorter, longer and easier picks and a filter for any ending or length.

O has 262 nouns. Ocean, orange and oil are concrete and easy to picture, while opinion, opportunity and origin name ideas.

The tion ending appears again and again: operation, organization, option. Orange is worth a quick lesson, because it can mean a colour as well as something you eat. Office, officer and owner are good for a 'people and places at work' theme. Occasion is often misspelled, so add it to a spelling test.

Nouns starting with O: 262
Most used: or
Longest common one: organization 12 letters

Most common nouns that start with O

Ranked by how often the word appears in English text. "Type" is the word's main part of speech.

#	Word	Meaning	Type
1	or	a state in northwestern United States on the Pacific	noun
2	order	(often plural) a command given by a superior (e.g., a military or law enforcement officer) that must be obeyed	noun
3	oh	a midwestern state in north central United States in the Great Lakes region	noun
4	office	place of business where professional or clerical duties are performed	noun
5	official	a worker who holds or is invested with an office	noun
6	oil	a slippery or viscous liquid or liquefiable substance not miscible with water	noun
7	officer	any person in the armed services who holds a position of authority or command	noun
8	opportunity	a possibility due to a favorable combination of circumstances	noun
9	opening	an open or empty space in or between things	noun
10	opinion	a personal belief or judgment that is not founded on proof or certainty	noun
11	operation	the state of being in effect or being operative	noun
12	organization	a group of people who work together	noun
13	operations	financial transactions at a brokerage; having to do with the execution of trades and keeping customer records	noun
14	owner	(law) someone who owns (is legal possessor of) a business	noun
15	option	the right to buy or sell property at an agreed price	noun
16	ocean	a large body of water constituting a principal part of the hydrosphere	noun
17	orange	round yellow to orange fruit of any of several citrus trees	noun
18	offering	something offered (as a proposal or bid)	noun
19	opposition	the action of opposing something that you disapprove or disagree with	noun
20	object	a tangible and visible entity; an entity that can cast a shadow	noun
21	origin	the place where something begins, where it springs into being	noun
22	output	final product; the things produced	noun
23	ownership	the relation of an owner to the thing possessed; possession with the right to transfer possession to others	noun
24	occasion	an event that occurs at a critical time	noun
25	oxford	a city in southern England to the northwest of London; site of Oxford University	noun
26	objective	the goal intended to be attained (and which is believed to be attainable)	noun
27	organisation	the persons (or committees or departments etc.) who make up a body for the purpose of administering something	noun
28	outcome	something that results	noun
29	operator	(mathematics) a symbol or function representing a mathematical operation	noun
30	odds	the likelihood of a thing occurring rather than not occurring	noun
31	opera	a drama set to music	noun
32	occasions	something you have to do	noun
33	offense	a lack of politeness; a failure to show regard for others; wounding the feelings or others	noun
34	oxygen	a nonmetallic bivalent element that is normally a colorless odorless tasteless nonflammable diatomic gas	noun
35	outfit	any cohesive unit such as a military company	noun
36	occupation	the principal activity in your life that you do to earn money	noun
37	opponent	a contestant that you are matched against	noun
38	oak	the hard durable wood of any oak; used especially for furniture and flooring	noun
39	organ	a fully differentiated structural and functional unit in an animal that is specialized for some particular...	noun
40	observation	the act of making and recording a measurement	noun
41	overview	a general summary of a subject	noun
42	ore	a mineral that contains metal that is valuable enough to be mined	noun
43	os	a mouth or mouthlike opening	noun
44	obligation	the social force that binds you to the courses of action demanded by that force; ; - John D.Rockefeller Jr	noun
45	outlook	a habitual or characteristic mental attitude that determines how you will interpret and respond to situations	noun
46	orientation	the act of orienting	noun
47	oven	kitchen appliance used for baking or roasting	noun
48	orbit	the (usually elliptical) path described by one celestial body in its revolution about another	noun
49	ordering	logical or comprehensible arrangement of separate elements	noun
50	orchestra	a musical organization consisting of a group of instrumentalists including string players	noun
51	organs	edible viscera of a butchered animal	noun
52	outlet	a place of business for retailing goods	noun
53	outbreak	a sudden violent spontaneous occurrence (usually of some undesirable condition)	noun
54	oath	a commitment to tell the truth (especially in a court of law)	noun
55	offence	the action of attacking an enemy	noun
56	overtime	work done in addition to regular working hours	noun
57	observer	a person who becomes aware (of things or events) through the senses	noun
58	obsession	an irrational motive for performing trivial or repetitive actions, even against your will	noun
59	onion	the bulb of an onion plant	noun
60	opener	the first event in a series	noun
61	owl	nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes	noun
62	outrage	a feeling of righteous anger	noun
63	oversight	an unintentional omission resulting from failure to notice something	noun
64	obesity	more than average fatness	noun
65	ops	no short meaning listed	noun
66	ounce	a unit of apothecary weight equal to 480 grains or one twelfth of a pound	noun
67	oppression	the act of subjugating by cruelty	noun
68	omega	the ending of a series or sequence; --Revelation	noun
69	objection	the act of expressing earnest opposition or protest	noun
70	occurrence	an event that happens	noun
71	offspring	the immediate descendants of a person	noun
72	obstacle	something immaterial that stands in the way and must be circumvented or surmounted	noun
73	onset	the beginning or early stages	noun
74	observatory	a building designed and equipped to observe astronomical phenomena	noun
75	offender	a person who transgresses moral or civil law	noun
76	oracle	an authoritative person who divines the future	noun
77	outreach	the act of reaching out	noun
78	optimism	the optimistic feeling that all is going to turn out well	noun
79	optimization	the act of rendering optimal	noun
80	oxide	any compound of oxygen with another element or a radical	noun
81	ottoman	a Turk (especially a Turk who is a member of the tribe of Osman I)	noun
82	ordinance	an authoritative rule	noun
83	organism	a living thing that has (or can develop) the ability to act or function independently	noun
84	optics	the branch of physics that studies the physical properties of light	noun
85	orphan	a child who has lost both parents	noun
86	orchard	garden consisting of a small cultivated wood without undergrowth	noun
87	organizer	a person who brings order and organization to an enterprise	noun
88	oasis	a fertile tract in a desert (where the water table approaches the surface)	noun
89	outskirts	outlying areas (as of a city or town)	noun
90	obstruction	any structure that makes progress difficult	noun
91	odyssey	a long wandering and eventful journey	noun
92	outsider	someone who is excluded from or is not a member of a group	noun
93	oyster	marine mollusks having a rough irregular shell; found on the sea bed mostly in coastal waters	noun
94	obedience	the act of obeying; dutiful or submissive behavior with respect to another person	noun
95	outing	a journey taken for pleasure	noun
96	odor	any property detected by the olfactory system	noun
97	ordeal	a severe or trying experience	noun
98	ox	an adult castrated bull of the genus Bos; especially Bos taurus	noun
99	octopus	tentacles of octopus prepared as food	noun
100	outset	the time at which something is supposed to begin	noun

Positive nouns that start with O

obsession
optimism
oasis
openness
originality
ovation
overture

Short nouns that start with O

or
order
oh
oil
owner
ocean
odds
opera
oak
organ
ore
os
oven
orbit
oath
onion
owl
ops
ounce
omega
onset
oxide
oasis
odor
ox
ozone
od
otter
obi
ode
orb
opal
opus
omen
ogre
ohm

Long nouns that start with O

opportunity
organization
operations
opposition
organisation
occupation
observation
obligation
orientation
oppression
occurrence
observatory
optimization
obstruction
ordination
originality
ornamental
outpatient
observance
objectivity
obstetrics
outfielder
osteoporosis
oscillation
oscillator
ophthalmology
occidental
originator
oceanography
outpouring

Filter all 262 nouns that start with O

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Questions people ask

How many nouns start with O?

This list has 262 nouns starting with O, taken from a standard word-game dictionary and limited to words that appear in real English text.

What are the most common nouns that start with O?

or, order, oh, office, official, oil, officer, opportunity are the most used in everyday English.

What are some long nouns that start with O?

opportunity, operation, organization, operations, opposition.

What are easy nouns that start with O for kids?

or, order, oh, office, oil, owner are short, everyday examples.

Source: the ENABLE word list (a public-domain dictionary used for word games), ranked by how often each word appears in English text (the open wordfreq project), with short meanings from Princeton WordNet. Offensive words are left out.

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