9-Letter Words Starting with O

All 232 nine-letter words that start with O

OB

• obbligato14n. An obbligato section; a prominent countermelody, often written to be...
• obduction14n. An autopsy.
• obedience14n. The quality of being obedient.
• obeisance13n. Demonstration of an obedient attitude, especially by bowing deeply; a...
• obfuscate16v. To make dark; to overshadow.
• objectify26v. To make (something, such as an abstract idea) possible to be perceived...
• objection20n. The act of objecting.
• objective23adj. Of or relating to a material object, actual existence or reality.
• obligated13adj. Committed.
• obliquely23adv. In an oblique manner; sideways.
• obliquity23n. The quality of being oblique in direction, deviating from the...
• obliviate14v. To forget; to wipe from existence.
• oblivious14adj. Lacking awareness; unmindful; unaware, unconscious of.
• obnoxious18adj. Extremely offensive or unpleasant; very annoying, contemptible, or...
• obscenely16adv. In an obscene manner; vulgarly.
• obscenity16n. Something that is obscene.
• obscurely16adv. In an obscure manner.
• obscuring14n. The process of making obscure; a concealing or darkening.
• obscurity16n. Darkness; the absence of light.
• obsequies20n. Funeral rites.
• observant14adj. Alert and paying close attention; watchful.
• observing15n. Observation.
• obsession11n. The quality of being obsessed; an unshakeable feeling that one topic or...
• obsessive14adj. Prone to cause obsession.
• obstetric13adj. Of or relating to obstetrics (the care of women during and after...
• obstinacy16n. The state, or an act, of stubbornness or doggedness.
• obstinate11adj. Stubbornly adhering to an opinion, purpose, or course, usually with...
• obstruent11adj. Causing obstruction; blocking up.
• obtrusive14adj. Of a person: overly assertive, bold, or domineering; pushy; also...
• obturator11n. An object used to obstruct a hole, such as a fissure of the palate.
• obviously17adv. In an obvious or clearly apparent manner.

OC

• occipital15adj. Of, pertaining to, or located within or near the occiput (back of the...
• occlusion13n. The process of occluding, or something that occludes.
• occlusive16adj. That tends to occlude.
• occultism15n. The study of the supernatural.
• occultist13n. A person who practises or studies occultism; a practitioner of, or...
• occupancy20n. The act of occupying, the state of being occupied or the state of being...
• occurrent13adj. Current, actual, occurring.
• occurring14n. An instance of something occurring; an event or happening.
• oceanside12adj. Located on the coast of an ocean.
• oceanview17adj. Overlooking the ocean.
• oceanwide15adj. Spanning the whole ocean.
• ocellated12adj. Of, pertaining to, resembling or having an ocellus.
• octagonal12adj. Shaped like an octagon, in having eight sides and eight angles.

OD

• odalisque19n. A female slave in a harem, especially one in the Ottoman seraglio.
• oddsmaker17n. A person who sets odds for gambling.
• odiferous13adj. Odoriferous; smelly.
• odourless10adj. Having no odour.

OE

• oenophile14n. A person who has a fondness or appreciation for wine.

OF

• offending17n. The act of committing an offence.
• offensive18adj. Causing offense; arousing a visceral reaction of disgust, anger...
• offertory18n. A prayer said or sung as an anthem while offerings of bread and wine...
• offhanded20adj. In a casual or curt style, without preparation or thought; impromptu...
• officiant17n. A person who officiates at a religious ceremony (in Christianity, at...
• officiate17v. To perform the functions of some office.
• officious17adj. Offensively intrusive or interfering in offering advice and services.
• offscreen17adj. Existing or happening outside the frame of the cinema or television...
• offspring18n. A person's daughter or son; a person's child.
• offstream17adj. Not located on a streambed.
• ofloxacin21n. A fluoroquinolone antibiotic C₁₈H₂₀FN₃O₄ composed of equal quantities...

OL

• olecranon11n. The bony process at the top of the ulna forming the point of the elbow.
• oleoresin9n. A homogeneous mix of essential oil and resin.
• olfaction14n. The sense of smell; the detection of airborne molecules.
• olfactory17adj. Concerning the sense of smell.
• oligarchy18n. A government run by and for only a few, often the aristocracy, the...
• oligopoly15n. An economic condition in which a small number of sellers exert control...

OM

• ombudsman16n. An appointed official whose duty is to investigate complaints...
• ominously14adv. In an ominous manner; with sinister foreboding.
• omniverse14n. The entire set of co-existing universes, multiverses, etc.

ON

• oncogenic14adj. Causing the formation of tumors.
• oncologic14adj. Of or pertaining to oncology.
• oncolytic16adj. That breaks up cancer cells.
• onionskin13n. A thin, strong, light, translucent paper; used especially for making...
• onlooking14adj. That is looking on; watching, observing.
• onomastic13adj. Of or relating to a personal or place name.
• onrushing13adj. Rushing or flowing forward.
• onslaught13n. A fierce attack.

OO

• oogenesis10n. The formation and development of an oocyte or ovum.

OP

• operating12adj. In operation; that operates.
• operation11n. The method by which a device performs its function.
• operative14adj. Effectual or important.
• operatory14adj. Of or relating to operations.
• opercular13adj. Relating to the operculum.
• operculum15n. A covering flap in animals and insects, such as a gill cover or the lid...
• ophiolite14n. An assemblage of mafic and ultramafic rock fragments of the ocean...
• opportune13adj. Suitable for some particular purpose.
• opposable15adj. Susceptible to being opposed or resisted.
• oppressed14adj. Subject to oppression.
• oppressor13n. Someone who oppresses another or others.
• optically16adv. Regarding or using optics.
• opticians13n. An optometry practice.
• optimally16adv. In an optimal manner.
• optimized23adj. That has undergone optimization.
• optimizer22n. A person in a large business whose task is to maximize profits and make...
• optometry16n. The art and science of vision and eye care.
• optronics13n. Optoelectronics.
• opulently14adv. In an opulent manner.
• opusculum15n. An opuscule; a short work.

OR

• orangeade11n. A soft drink or a soda with an orange flavor.
• orangutan10n. An arboreal ape, characterised by its shaggy reddish-brown coat and...
• orbicular13adj. Circular or spherical in shape; round.
• orchestra14n. A large group of musicians who play together on various instruments...
• orderable12adj. That may be ordered (obtained by placing an order).
• ordinaire10n. Wine for ordinary use.
• ordinance12n. A local law, passed by e.g. a city.
• ordinator10n. One who ordains or establishes; a director.
• organelle10n. A specialized structure found inside cells that carries out a specific...
• organized20adj. Of things or settings, having been organized; in good order.
• organizer19n. A person who arranges the details of a public event.
• organotin10adj. Describing any organic compound containing a carbon to tin bond.
• orgiastic12adj. Relating to an orgy; uncontrolled, wild.
• orientate9v. To face a given direction.
• oriflamme16n. The red silk banner of St Denis, which the abbot of St Denis gave to...
• originary13adj. Pertaining to or being the origin of something.
• originate10v. To cause (someone or something) to be; to bring (someone or something)...
• ornithine12n. An amino acid, 2,5-diaminopentanoic acid, that is not present in...
• orofacial14adj. Of or affecting both the mouth and face.
• orography18n. The scientific study, or a physical description of mountains.
• orphanage15n. A residential institution for the care and protection of orphans.
• orthodoxy23n. Correctness of doctrine and belief in regard to any doctrinal (i.e....
• orthoptic16adj. Relating to orthoptics, the study and treatment of muscular...
• orthotics14n. The design, manufacture and installation of orthopedic appliances to...
• orthotist12n. A person who makes or fits orthotic devices.

OS

• oscillate11v. To swing back and forth, especially if with a regular rhythm.
• osmanthus14n. Any of several widely distributed evergreen flowering plants, of the...
• ostensive12adj. Apparently true, but not necessarily; ostensible.
• osteology13n. The scientific study of the morphology and pathology of bones.
• osteopath14n. A non-physician healthcare practitioner who practices osteopathy by...
• osteotomy14n. The surgical procedure of cutting a bone. This is often performed to...
• ostracism13n. In ancient Athens (and some other cities), the temporary banishment by...
• ostracize20v. To ban a person from a city for five or ten years through the procedure...

OT

• otherness12n. The quality of being different or distinct.
• otherways18adv. Otherwise; by another means; in other respects.
• otherwise15adv. Differently, in another way.
• otoplasty14n. A procedure of plastic surgery used to change the appearance or shape...

OU

• oubliette11n. A dungeon only accessible by a trapdoor at the top.
• ouroboros11n. A serpent, dragon or worm that eats its own tail, a representation of...
• ourselves12pron. Us; the group including the speaker as the object of a verb or...
• outdoorsy13adj. Associated with the outdoors, or suited to outdoor life.
• outermost11n. That which is outermost.
• outerwear12n. Clothing (such as a dress) worn over one's underwear.
• outfitter12n. A person or shop that sells specialized clothes and equipment.
• outgrowth16n. A branch or offshoot of a plant.
• outgunned11adj. Having insufficient guns compared to the enemy.
• outlander10n. A foreigner or alien.
• outlaying13n. Money spent; expenditure.
• outmuscle13v. To surpass in a contest involving strength.
• outnumber13v. To be more in number than somebody or something.
• outraging11n. The committing of an outrage.
• outrigger11n. Any of various projecting beams or spars that provide support for a...
• outsiders10n. A pair of nippers for turning a key in a keyhole from the outside.
• outskirts13n. The area surrounding a city or town; suburb.
• outsource11v. To transfer the management or day-to-day execution of a business...
• outspoken15adj. Speaking, or spoken, freely, openly, or boldly; vocal; frank.
• outspread12v. To spread out; expand; extend.
• outwardly16adv. Externally or on the outside, or on the surface.

OV

• ovalbumin16n. A glycoprotein which is the primary constituent of egg white.
• ovenproof17adj. Suitable for use in an oven, without being damaged by the heat.
• overblown17adj. Of exaggerated importance; too heavily emphasized, hyped, etc.
• overboard15adj. Outside of a boat; in the water.
• overboost14v. To increase an engine's intake manifold pressure to higher levels than...
• overbroad15adj. Too broad.
• overbuild15v. To perform excessive construction on a building or in an area.
• overbuilt14adj. Overdeveloped.
• overclock20v. To run a processor (CPU), or any electronic logic device, at a speed...
• overcomer16n. One who overcomes.
• overcrowd18v. To fill beyond reasonable limits, with people, animals, objects or...
• overdoing14n. Excessive activity.
• overdraft16n. The act of overdrawing a bank account.
• overdrawn16adj. Portrayed in an overstated or exaggerated manner.
• overdress13v. To wear too many clothes for a particular occasion.
• overdrive16v. To drive too hard, or far, or beyond strength.
• overeager13adj. Excessively eager.
• overexert19v. To exert (oneself) to an excessive degree.
• overglaze22n. The outer layer or coat of glaze on a piece of pottery.
• overgrown16adj. Having large numbers of plants which have become too big, and are hence...
• overhauls15n. An overall.
• overhyped21adj. That has been promoted or publicized excessively.
• overjoyed23adj. Very happy.
• overladen13adj. Packed heavily, especially beyond normal capacity; overloaded.
• overlying16adj. Lying over or upon something else.
• overmatch19v. To match more than intended.
• overnight16adv. During or throughout the night, especially during the evening or night...
• overpower17v. To subdue someone by superior force.
• overprice16v. To give a commodity an excessive price.
• overprint14n. An addition of new text on a previously printed stamp, usually to add a...
• overproof17adj. Possessing a higher proportion of alcohol than proof spirit.
• overrated13adj. Given an undue amount of credit for quality or merit in a field; not...
• overreach17v. To reach above or beyond, especially to an excessive degree.
• overreact14v. To react too much or too intensely.
• oversexed20adj. Having a greater than normal sexual appetite.
• overshare15v. To share too much or in excess.
• overshoot15n. The amount by which something goes too far.
• oversight16n. An omission; something that is left out, missed, or forgotten.
• oversized22adj. Very large; especially of something larger than normal for its type.
• overskirt16n. A skirt worn visibly, especially over another layer, such as a...
• oversleep14v. To sleep for longer than intended.
• overspeed15v. To travel excessively fast or beyond the permitted rate.
• overspend15v. To spend too much money; especially, to spend more than one earns.
• overspent14adj. Exhausted; excessively fatigued.
• overspill14n. That which spills over.
• overspray17n. In spray painting, the spray that goes outside the area being painted...
• overstate12v. To state or claim too much.
• oversteer12n. The condition in which the rear wheels of a car don't follow the...
• overstock18v. To stock to an excessive degree.
• overstory15n. The upper portion of a community of plants, above the understory.
• overtaken16adj. Taken by surprise; overcome.
• overthink19v. To think or analyze too much.
• overthrow18v. To bring about the downfall of (a government, etc.), especially by...
• overtired13adj. Overly tired.
• overtrain12v. To train too much or too long.
• overvalue15v. To assign an excessive value to something.
• overwatch20v. To watch over.
• overwater15adj. By or across water, especially of travel.
• overwhelm20v. To engulf, surge over and submerge.
• overworld16n. The celestial world.
• overwrite15v. To destroy (older) data by recording new data over it.
• oviparous14adj. Depositing eggs that develop and hatch outside the body as a...
• oviraptor14n. Any of several bipedal dinosaurs, of the genus Oviraptor, from the late...
• ovulation12n. The release of an ovum from an ovary.
• ovulatory15adj. Pertaining to ovulation; ovulating.

OW

• ownerless12adj. Having no owner.
• ownership17n. The state of having complete legal control of something; possession...

OX

• oxacillin18n. A narrow-spectrum beta-lactam antibiotic made by chemical modification...
• oxazoline25n. An unsaturated heterocyclic compound containing a five-membered ring...
• oxidation17n. The combination of a substance with oxygen.
• oxidative20adj. Of, relating to, or produced by oxidation.
• oxidizing27adj. That oxidizes.
• oxycodone22n. An addictive, semisynthetic opioid (trademark OxyContin) that is...
• oxygenase20n. An enzyme which catalyses biochemical reactions with oxygen.
• oxygenate20v. To treat or infuse with oxygen.

OZ

• ozonation18n. The act of treating with ozone.

Questions about these words

How many nine-letter words that start with O are there?

Word.ws lists 232 nine-letter words that start with O, plus 1,299 rare ones.

What are common nine-letter words that start with O?

operation, otherwise, obviously, operating, ourselves, organized, offensive and ownership.

Which of the nine-letter words that start with O has the highest letter score?

oxidizing scores 27 points with the standard letter tile values.

Related word lists

• 9-Letter Words
• Words That Start with O
• 8-Letter Words Starting with O
• 10-Letter Words Starting with O
• Q Words Without U