10-Letter Words Starting with O

All 203 ten-letter words that start with O

OB

• obdurately16adv. In an obdurate manner; stubbornly, intractably or inflexibly.
• obediently16adv. In an obedient manner.
• obesogenic15adj. Causing obesity.
• obfuscated18adj. Having undergone obfuscation.
• oblateness12n. The state of being oblate.
• obligately16adv. In an obligate manner.
• obligation13n. The act of binding oneself by a social, legal, or moral tie to someone.
• obligatory16adj. Imposing obligation, legally, morally, or otherwise; binding; mandatory.
• obligingly17adv. In an obliging manner; so as to oblige another; as a favour to another.
• obliterans12adj. Producing obstruction due to inflammation and fibrosis.
• obliterate12v. To destroy (someone or something) completely, leaving no trace; to...
• obsequious21adj. Excessively eager and attentive to please or to obey instructions...
• observable17adj. Able to be observed.
• observably20adv. To a detectable degree, sufficient to be observed.
• observance17n. The practice of complying with a law, custom, command or rule.
• observator15n. An observer.
• obsoletely15adv. When out of date or no longer in use.
• obstetrics14n. The care of women during and after pregnancy.
• obstinance14n. The characteristic of being obstinate.
• obtainable14adj. Able to be obtained.
• obtainment14n. The act of obtaining something; acquisition.
• obturation12n. The act of stopping up, or closing, an opening.
• obtuseness12n. The quality of being obtuse.

OC

• occasional14adj. Occurring or appearing irregularly from time to time, but not often...
• occidental15adj. Of, pertaining to, or situated in, the occident, or west; western.
• occupation16n. An activity or task with which one occupies oneself; usually...
• occurrence16n. An actual instance when a situation occurs; an event or happening.
• oceanarium14n. A park where visitors can see marine mammals and/or fish.
• oceanfront15adj. Of property or real estate: adjacent to the ocean.
• oceangoing14adj. Travelling out to sea.
• oceanology16n. Oceanography.
• ochraceous17adj. Ochre-colored.
• ochratoxin22n. Any of a class of mycotoxins, having an isocoumarin structure, produced...
• octahedral16adj. Of, relating to, or having the shape of an octahedron.
• octahedron16n. A polyhedron with eight faces; the regular octahedron has regular...
• octocopter16n. An unmanned rotorcraft having eight rotors.
• octopamine16n. An aromatic amine, 4-(2-amino-1-hydroxy-ethyl)phenol, related to...
• octreotide13n. An octapeptide that mimics natural somatostatin pharmacologically...
• oculomotor14adj. Of or pertaining to movement of the eyeball.

OD

• odontology15n. The study of the structure and development of teeth.

OE

• oenologist11n. An expert in the science of oenology.
• oesophagus16n. The tube that carries food from the pharynx to the stomach.
• oestradiol11n. British standard spelling of estradiol.

OF

• officially21adv. In an official manner; according to official rules or regulations.
• officiator18n. A person who officiates.
• offloading18n. The act by which something is offloaded.
• offsetting17n. The use of one thing to offset another; the practice of compensating...
• offshoring20n. The location of a business in another country for tax purposes or...
• oftentimes15adv. Frequently; often.

OL

• olanzapine21n. An antipsychotic drug C₁₇H₂₀H₄S administered orally especially in the...
• oleaginous11adj. Oily, greasy.
• oleophobic19adj. Tending to repel oil.
• oligarchic18adj. Of or pertaining to oligarchy.
• oligomeric15adj. Of, pertaining to, or being an oligomer.
• olivaceous15adj. Having the color of a green olive.
• olmesartan12n. An angiotensin-receptor antagonist used to treat hypertension.

OM

• omalizumab25n. A monoclonal antibody used mainly in allergy-related asthma therapy...
• omeprazole23n. A substituted benzimidazole (trademark Losec, Prilosec) which is a...
• omnipotent14adj. Having unlimited power, force or authority.
• omniscient14adj. Having total knowledge.
• omnisexual19adj. Being attracted to all genders (sometimes distinguished from pansexual...
• omnivorous15adj. Having a diet which is neither exclusively carnivorous nor exclusively...

ON

• onboarding14n. The process of bringing a new employee on board, incorporating training...
• oncologist13n. A doctor or scientist who specializes in oncology.
• onomastics14n. The branch of lexicology devoted to the study of names and naming...

OP

• opalescent14adj. Exhibiting a milky iridescence like that of an opal.
• opaqueness21n. Synonym of opacity.
• operations12n. Any practically minded combination of business administration...
• operculate14adj. Having an operculum.
• ophiolitic17adj. Of or pertaining to sections of the oceanic crust and the subjacent...
• ophthalmia20n. Synonym of ophthalmitis (“inflammation of the eye”).
• ophthalmic22adj. Of or pertaining to the eyes.
• oppositely17adv. In an opposite manner.
• opposition14n. The action of opposing or of being in conflict.
• oppressing15adj. Oppressive.
• oppression14n. The exercise of authority or power in a burdensome, cruel, or unjust...
• oppressive17adj. Burdensome or difficult to bear.
• opprobrium18n. Disgrace or bad reputation arising from exceedingly shameful behaviour...
• optimality17n. The property of being optimal.
• optimistic16adj. Expecting the best in all possible ways.
• optimizing24adj. Carrying out optimization.
• optionally15adv. In an optional manner; not mandatorily.
• optometric16adj. Of or pertaining to optometry.

OR

• orangewood15n. The wood of the orange tree.
• oratorical12adj. Of, or relating to oratory or an orator.
• orchardist16n. Synonym of orcharder.
• orchestral15adj. Relating to an orchestra or to music played by an orchestra.
• ordinarily14adv. Usually or as a general rule; commonly.
• ordination11n. The act of ordaining or the state of being ordained.
• ordonnance13n. The disposition of the parts of any composition with regard to one...
• organellar11adj. Of or pertaining to organelles.
• organicism15n. The theory that disease is a result of structural alteration of organs.
• organigram14n. A graphical representation of the structure of an organization, showing...
• organising12n. The act or process by which something is organised.
• organismal13adj. Of or relating to an organism or organisms.
• organismic15adj. Of or relating to organicism or organisms.
• organizing21n. The act or process by which something is organized.
• orichalcum19n. A valuable yellow metal known to the Ancient Greeks and Romans; now...
• orientable12adj. Able to be oriented.
• orientalia10n. Things from the Orient, especially decorative objects from eastern Asia.
• originally14adv. As it was in the beginning; at first.
• originator11n. Someone who originates, creates or founds something.
• ornamental12adj. Serving as an ornament; having no purpose other than to make more...
• orographic18adj. Of or pertaining to the physical features of mountains, or to orography.
• oropharynx25n. The oral part of the pharynx, reaching from the uvula to the level of...
• orthoceras15n. Any nautiloid cephalopod mollusc of the genus Orthoceras, known only as...
• orthoclase15n. Potassium aluminum silicate, KAlSi₃O₈, a common feldspar of igneous...
• orthogonal14adj. Of two objects, at right angles; perpendicular to each other.
• orthopedic18adj. Of or relating to orthopedics.
• orthophoto18n. An aerial photograph that has been geometrically corrected...
• orthopraxy25n. Correctness of practice or action in regard to religion and especially...
• orthoptera15n. Any of very many four-winged insects, of the order Orthoptera, such as...
• orthorexia20n. A fixation with healthy or righteous eating.
• orthotopic17adj. In the normal position.

OS

• oscillator12n. A tuned electronic circuit used to generate a continuous output...
• osculating13adj. Having three or more points coincident with another.
• osmolality15n. The molality of an ideal solution that would exert the same osmotic...
• osmolarity15n. The osmotic concentration of a solution, normally expressed as osmoles...
• ostensible12adj. Apparent, evident; meant for open display.
• ostensibly15adv. Seemingly, apparently, on the surface; supposedly, according to...
• osteoblast12n. A mononucleate cell from which bone develops.
• osteoclast12n. A large multinuclear cell associated with the resorption of bone.
• osteogenic13adj. Of, or relating to, osteogenesis.
• osteolysis13n. The resorption or dissolution of bone tissue.
• osteolytic15adj. Of, pertaining to, or causing osteolysis.
• osteopathy18n. The branch of therapy based on manipulation of bones and muscles.
• osteopenia12n. The medical condition of having low bone density, but not low enough to...
• ostracized22adj. Blackballed.

OT

• otherwhere19adv. Synonym of somewhere else: elsewhere, in or to some other place.
• otherworld17n. A world beyond death; an afterlife.

OU

• outcompete16v. To be more successful than a competitor; especially to thrive in the...
• outfielder14n. A player that plays in the outfield, which is the outer portion of the...
• outfitting14n. A furnishing or accoutrement.
• outflowing17adj. Flowing out.
• outgassing12n. The slow release of gas from a solid or liquid; especially, the release...
• outgrowing15n. That which grows outward; outgrowth.
• outlandish14adj. Appearing to be foreign; strange, unfamiliar.
• outmatched18adj. Overwhelmed by adversarial forces or circumstances (either animate or...
• outmuscled15adj. Overcome by superior strength.
• outpatient12n. A patient who receives treatment at a hospital or clinic but is not...
• outperform17v. To perform better than something or someone.
• outpouring13n. The sudden outward flowing of a large amount of something.
• outrageous11adj. Violating morality or decency; provoking indignation or affront.
• outrightly17adv. Outright.
• outshining14n. A shining outward; effulgence.
• outsourced13adj. Obtained by outsourcing.
• outsourcer12n. One who outsources.
• outstation10n. A station or post in a remote position; an outpost.
• outworking18n. The process by which something is carried out or accomplished; the act...

OV

• overactive18adj. Excessively active.
• overbooked20adj. Having had more seats, tickets, or slots sold or guaranteed than were...
• overbought19adj. Of a stock or commodity market condition: where there has been...
• overbridge17n. A bridge that allows traffic to pass over a road, river, railway etc.
• overbudget17adj. Costing more than budgeted.
• overburden16v. To overload or overtax.
• overcharge19v. To charge (somebody) more money than the correct amount or to surpass a...
• overcoming18n. The act by which something is overcome, or surmounted.
• overcommit19v. To make excessive commitments, either beyond one's ability or beyond...
• overcooked20adj. Made unpalatable or inedible by cooking for too long.
• overdosage15n. An excessive dosage; taking too much of a pharmaceutical drug.
• overdosing15n. An excessively large dose.
• overdriven17adj. Driven too hard, or beyond normal limits; exhausted.
• overeating14n. Gluttony, the act of eating to excess.
• overexpose22v. To expose excessively.
• overextend21v. To expand or extend to an excessive degree, especially to do so beyond...
• overfished20adj. Fished to the point of sustained reduction of fish species population.
• overflight20n. The flight of an aircraft over a particular place; used especially to...
• overground15adj. Above the ground.
• overgrowth20n. A usually abundant, luxuriant growth over or on something else.
• overheated17adj. Excessively heated.
• overlander14n. One who travels overland.
• overlaying17n. Overlaid ornamentation.
• overloaded15adj. Loaded too heavily.
• overlooked18adj. Missed, unnoticed.
• overmanned16adj. Excessively manned; overstaffed.
• overmantel15n. A decorative structure, usually plasterwork or carved wood, and...
• overplayed19adj. Played too frequently.
• overpraise15v. To do so toward a person.
• overpriced18adj. Priced higher than its real worth.
• overriding15n. The act or process by which something is overridden.
• overruling14n. The situation where something is overruled.
• oversample17n. An additional sample of a subpopulation, above and beyond the portion...
• overshadow20v. To obscure something by casting a shadow.
• overspread16v. To spread over or across (something); cover over; be scattered over...
• overstated14adj. Having been overstated; exaggerated; stated, displayed, or presented...
• overstrain13v. To subject to an excessive demand on strength, resources, abilities, or...
• overstress13v. To place excessive emphasis on something.
• oversupply20v. To supply more than is needed.
• overtaking18n. The act by which one thing overtakes another.
• overthrust16n. A form of thrust fault from beneath a hanging wall of rock.
• overweight20adj. Having a higher weight, especially body fat, than what is generally...
• overwinter16v. To keep or preserve for the winter.
• overworked21adj. Subjected to too much work.
• ovipositor15n. A tubular protruding organ for laying eggs.

OX

• oxadiazole27n. Any five-membered heterocycle having two carbon atoms, two nitrogen...
• oxidizable29adj. Capable of being oxidized.
• oxybenzone31n. A benzophenone compound widely used in sunscreens and plastics.
• oxybutynin25n. An antispasmodic and anticholinergic drug C₂₂H₃₁NO₃ administered...
• oxygenated22adj. Containing oxygen, or oxygen-containing radicals, as substituents.
• oxygenator21n. Any device that releases oxygen (or air) into water, especially one in...
• oxymoronic24adj. Of or pertaining to an oxymoron.
• oxynitride21n. Any of several inorganic compounds of the general formula Mₓ(ON)_y...

OZ

• ozonolysis22n. Any reaction with ozone, especially to a double bond, in which cleavage...

Questions about these words

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

Word.ws lists 203 ten-letter words that start with O, plus 1,376 rare ones.

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

operations, originally, opposition, officially, occupation, occasional, obligation and organizing.

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

oxybenzone scores 31 points with the standard letter tile values.

Related word lists

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