Words That Start With O: 500+ O Words

If you’re a writer, it’s a good idea to develop a broad vocabulary to use in your writing projects.

Using a variety of words will make your writing sound more interesting because you’ll likely create new phrases your reader hasn’t heard before. Everyone can benefit from more interesting writing, even those just writing emails, because it results in more engaged readers.

In this article, we’ll give you 500+ words that start with O, which you can use to broaden your vocabulary and create more engaging writing.

Things That Start With O

There are hundreds of nouns starting with O, which are words that identify things, such as places, people, and objects.

When you’re writing, you’ll need to include plenty of nouns so your reader knows what you’re writing about.

For example, you could write a story about a person who is an oboist, eating oatmeal for breakfast before his big recital where he’ll be under observation from his instructor.

Here’s a list of nouns that start with O:

• Oak

• Oatmeal

• Oblivion

• Oboist

• Observation

• Obstructionist

• Occupation

• Ocean

• Offer

• Officer

• Olive

• Onion

• Ooze

• Opera

• Opinion

• Opium

• Opponent

• Oppression

• Optimism

• Optimization

• Oracle

• Orchard

• Ordeal

• Orderly

• Ordinary

• Organ

• Organist

• Organization

• Orientation

• Origin

• Original

• Ornament

• Ornamentation

• Orphan

• Orthodontist

• Orthophosphate

• Oscillation

• Osmium

• Otter

• Outback

• Outbreak

• Outburst

• Outcast

• Outcome

• Outfield

• Outfielder

• Outfit

• Outflow

• Outgrowth

• Outhouse

• Outing

• Outlay

• Outline

• Outpatient

• Outpost

• Outpouring

• Outrage

• Outreach

• Outset

• Outside

• Outsider

• Oval

• Ovation

• Oven

• Overall

• Overcast

• Overcoat

• Overcrowding

• Overestimation

• Overexploitation

• Overflow

• Overhang

• Overhaul

• Overhead

• Overheating

• Overload

• Overpayment

• Overpopulation

• Overprotection

• Overrun

• Overseer

• Oversight

• Oversimplification

• Overthrow

• Overtime

• Overture

• Overweight

• Owl

• Owner

• Ownership

• Owning

• Oxalate

• Oxcart

• Oxen

• Oxidation

• Oxide

• Oxygen

• Oyster

• Ozone

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Positive Words Beginning With O

Positive words are perfect for your writing when you need to create a happy, jolly tone. You can add more positive words that start with O if you want to let your reader know something good has happened or if you need to describe something you want your readers to like.

Here’s a list of positive words that start with O:

• Oaken

• Oasis

• Obedience

• Obedient

• Objective

• Obliging

• Observant

• Observative

• Obsession

• Occur

• Ocean

• Ocular

• Ode

• Odyssey

• Ogle

• Ohana

• Okay

• Olympiad

• Olympian

• Omnipresent

• One-of-a-kind

• Onward

• Oomph

• Open

• Open-hearted

• Open-minded

• Openness

• Operate

• Operative

• Opportune

• Opportunity

• Optimal

• Optimism

• Optimistic

• Option

• Opulence

• Opulent

• Oracle

• Order

• Orderly

• Ordinance

• Organic

• Organized

• Origin

• Original

• Originality

• Ornate

• Ostentation

• Outcome

• Outgoing

• Outlander

• Outlook

• Outpace

• Outperform

• Outpouring

• Outreach

• Outshine

• Outspoken

• Outstanding

• Ovation

• Overabundance

• Overachieve

• Overachievement

• Overcomer

• Overflowing

• Overjoyed

• Overload

• Own

6-Letter Words Starting With O

If you’re playing a word game, like a crossword, and you need a six-letter word starting with O, there are hundreds of them to choose from.

You can pick one of the O words in our list and check the definition using the ProWritingAid Word Explorer to see if it fits the clue you’ve been given.

Here’s a list of six-letter words that start with O:

• Obtuse

• Occult

• Occupy

• Oculus

• Odylic

• Ogling

• Ohmage

• Oiling

• Olives

• Omegas

• Omelet

• Oniony

• Online

• Onside

• Onward

• Onyxis

• Oodles

• Oolong

• Oozier

• Opener

• Ophite

• Opiate

• Opioid

• Oppose

• Optics

• Opting

• Orally

• Ordain

• Orfray

• Organs

• Origan

• Origin

• Orison

• Ormers

• Ornery

• Orphan

• Orphic

• Orpine

• Oryxes

• Ostium

• Ostomy

• Others

• Otiose

• Otitis

• Otters

• Ounces

• Ousted

• Ouster

• Outage

• Outate

• Outbid

• Outeat

• Outens

• Outfit

• Outfox

• Outgun

• Outing

• Outrun

• Outset

• Outwit

• Ovally

• Ovaria

• Overdo

• Overed

• Overly

• Owlets

• Owlish

• Owners

• Owning

• Oxidic

• Oxlips

• Oxtail

• Oxygen

• Ozones

7-Letter Words Starting With O

Seven-letter words are perfect for word games, such as Scrabble and Words With Friends, where you can use up all your tiles and potentially achieve a high score.

It’s sometimes difficult to create a seven-letter word in Scrabble, but if you learn more seven-letter words, you will give yourself a better chance of remembering one you can use.

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Here’s a list of seven-letter words that start with the letter O:

• Observe

• Obtains

• Ocarina

• Octavus

• Octuple

• Oddness

• Odylism

• Offcast

• Offhand

• Offices

• Oilseed

• Olivary

• Omitted

• Omitter

• Onesies

• Onstage

• Opacify

• Opaline

• Opaques

• Operand

• Operate

• Opioids

• Opposer

• Opposes

• Options

• Oraches

• Oracles

• Oralist

• Oranges

• Oratory

• Orblike

• Orchids

• Ordains

• Ordered

• Organon

• Orients

• Orisons

• Orrises

• Osmosis

• Osteoid

• Outages

• Outbawl

• Outcast

• Outchid

• Outdone

• Outglow

• Outgrow

• Outjinx

• Outkiss

• Outlaid

• Outlast

• Outlaws

• Outplay

• Outpost

• Outtake

• Ovarian

• Ovately

• Overate

• Overbuy

• Overdry

• Overfed

• Overjoy

• Overran

• Oversaw

• Oversea

• Oversee

• Overtly

• Overuse

• Ovonics

• Ovulate

• Oxalate

• Oxblood

• Oxidant

• Oxidate

• Oxidize

• Oxtails

• Oxygens

• Ozonous

8-Letter Words That Begin With O

There are many eight-letter words you can use in your writing or word games. Any of the words in our list could come up in a crossword puzzle, or you could use one in a game of hangman to test your friends’ knowledge of O words.

Here’s a list of eight-letter words that start with O:

• Obituary

• Obligers

• Observer

• Obstruct

• Obtrudes

• Obviable

• Obviator

• Officers

• Offprint

• Ogreisms

• Ommateum

• Omnivore

• Onlooker

• Ooziness

• Opalesce

• Operable

• Operably

• Opticist

• Optimums

• Optioned

• Ornately

• Outacted

• Outboard

• Outcourt

• Outdates

• Outlasts

• Outlaugh

• Outlines

• Outlived

• Outlooks

• Outpours

• Outrages

• Outreach

• Ovalness

• Ovaritis

• Overages

• Overbear

• Overcull

• Overdone

• Overdraw

• Overgrew

• Overhand

• Overlies

• Overline

• Overpaid

• Overrule

• Oversees

• Oversell

• Oversold

• Overword

• Oviducts

• Ovulated

• Owlishly

• Oxalises

• Oximeter

• Oxytones

• Ozonized

Best Words Starting With O for Scrabble

If you’re playing Scrabble, and you want to be sure of a higher score, using certain tiles such as Z (10), Q (10), X (8), and J (8) will help you, as they’re the highest-scoring tiles in the game. There are many words that start with O containing one or more of the high-scoring letters.

Here’s a list of high-scoring Scrabble words that start with O:

• Obelize (18)

• Objects (18)

• Oblique (18)

• Obloquy (21)

• Obsequy (21)

• Odorize (17)

• Ooziest (16)

• Opaqued (19)

• Opaques (18)

• Oquassa (16)

• Oratrix (14)

• Organza (17)

• Outgaze (17)

• Outjest (14)

• Outjinx (21)

• Outjump (18)

• Outjuts (14)

• Outsize (16)

• Overjoy (20)

• Overlax (17)

• Overmix (19)

• Overtax (17)

• Oxalate (14)

• Oxazine (23)

• Oxblood (17)

• Oxcarts (16)

• Oxfords (18)

• Oxheart (17)

• Oxidant (15)

• Oxidase (15)

• Oxidate (15)

• Oxidize (24)

• Oxtails (14)

• Oxyacid (20)

• Oxygens (18)

• Oxymora (19)

• Oxysalt (17)

• Oxytone (17)

• Ozonide (17)

• Ozonous (16)

There you go, over 500 words that start with O for you to familiarize yourself with and show off when you’re playing word games.

Use the ProWritingAid Word Explorer to find out the definitions, synonyms, and rhyming words for any of the words on our lists. You can access the ProWritingAid Word Explorer from the ProWritingAid website. It’s a great free tool to use when you’re writing and editing.

We hope the O words in this article will help you create more interesting writing and win many word games.