Words starting with O — 407 entries

The 407 dictionary words that begin with the letter O, in alphabetical order, each with its first definition. Accents do not affect filing: an accented initial is shelved under its base letter.

• o4 sensesThe fifteenth letter of the English alphabet, called o and written in the Latin script.
• O14 sensesThe fifteenth letter of the English alphabet, called o and written in the Latin script.
• oaf3 sensesA person, especially a large male, who is clumsy or a simpleton.
• oak14 sensesA deciduous tree with distinctive deeply lobed leaves, acorns, and notably strong wood, typically of England and northeastern North America, included…
• Oakland12 sensesA township in Ontario, Canada.
• oaks1 senseA stakes race in which entry is restricted to 3-year-old fillies.
• Oaks8 sensesA surname.
• oasis3 sensesA spring of fresh water, surrounded by a fertile region of vegetation, in a desert.
• Oasis2 sensesA census-designated place in Riverside County, California, United States.
• oath5 sensesA solemn pledge or promise that invokes a deity, a ruler, or another entity (not necessarily present) to attest the truth of a statement or sincerity…
• oatmeal4 sensesMeal made from rolled or round oats.
• oats3 sensesA mass of oat plants (genus Avena, especially Avena sativa).
• Obama5 sensesAn African surname from Luo.
• obedience4 sensesThe quality of being obedient.
• obedient2 sensesWilling to comply with the commands, orders, or instructions of those in authority; biddable.
• obey3 sensesTo do as ordered by (a person, institution etc), to act according to the bidding of.
• obituary5 sensesA brief notice of a person's death, especially one published in a newspaper or other publication; also (obsolete), the section of a newspaper where…
• object11 sensesA thing that has physical existence but is not alive.
• objection4 sensesThe act of objecting.
• objective11 sensesOf or relating to a material object, actual existence or reality.
• obligated2 sensesCommitted.
• obligation5 sensesThe act of binding oneself by a social, legal, or moral tie to someone.
• oblige3 sensesTo constrain someone by force or by social, moral or legal means.
• obliged2 sensesUnder an obligation to do something.
• oblivion5 sensesThe state of forgetting completely, of being oblivious, unconscious, unaware, as when sleeping, drunk, or dead.
• oblivious2 sensesLacking awareness; unmindful; unaware, unconscious of.
• obnoxious7 sensesExtremely offensive or unpleasant; very annoying, contemptible, or odious.
• obscene6 sensesOffensive to standards of decency or morality.
• obscure8 sensesDark, faint or indistinct.
• observant3 sensesAlert and paying close attention; watchful.
• Observant1 senseA member of a Franciscan order that strictly observes the rules of St. Francis.
• observation8 sensesThe act of observing, and the fact of being observed (see observance)
• observatory2 sensesA place where stars, planets and other celestial bodies are observed, usually through a telescope; also place for observing meteorological or other…
• observe5 sensesTo notice or view, especially carefully or with attention to detail.
• observed1 senseExceptionally celebrated on a date other than the usual date.
• observer7 sensesOne who makes observations, monitors or takes notice.
• observing2 sensesobservation
• obsessed2 sensesIntensely preoccupied with or by a given topic or emotion; driven by a specified obsession.
• obsession4 sensesThe quality of being obsessed; an unshakeable feeling that one topic or activity must be pursued above other interests.
• obsessive4 sensesProne to cause obsession.
• obsolete4 sensesNo longer in use or no longer useful; now disused or neglected (often in favour of something newer, better, or more fashionable); outmoded.
• obstacle1 senseSomething that impedes, stands in the way of, or holds up progress, either physically or figuratively
• obstinate3 sensesStubbornly adhering to an opinion, purpose, or course, usually with implied unreasonableness; persistent.
• obstruction3 sensesThe act of obstructing, or state of being obstructed.
• obtain5 sensesTo get hold of; to gain possession of, to procure; to acquire, in any way.
• obvious1 senseEasily discovered, seen, or understood; self-explanatory.
• obviously2 sensesIn an obvious or clearly apparent manner.
• occasion10 sensesA favorable opportunity; a convenient or timely chance.
• occasional5 sensesOccurring or appearing irregularly from time to time, but not often; incidental.
• occasionally3 sensesOn occasion: at relatively infrequent intervals, from time to time, sometimes.
• occult7 sensesTo cover or hide from view.
• occupation3 sensesAn activity or task with which one occupies oneself; usually specifically the productive activity, service, trade, or craft for which one is…
• occupational1 senseOf, belonging, or relating to an occupation (in any sense).
• occupied4 sensesReserved; engaged.
• occupy11 sensesTo take or use. To fill.
• Occupy1 senseSynonym of OWS (“"Occupy Wall Street" protest movement”).
• occur4 sensesTo happen or take place.
• occurrence2 sensesAn actual instance when a situation occurs; an event or happening.
• occurring2 sensesAn instance of something occurring; an event or happening.
• ocean4 sensesOne of the large bodies of water separating the continents.
• Ocean4 sensesA female given name from English, of modern usage.
• October4 sensesThe tenth month of the Gregorian calendar, following September and preceding November.
• octopus12 sensesAny of several marine molluscs of the order Octopoda, having no internal or external protective shell or bone (unlike the nautilus, squid and…
• od2 senses(Euphemistic form of) God.
• Od1 senseAn Indo-Aryan language spoken in Sindh and Punjab in Pakistan and Gujarat, Haryana, New Delhi and Rajasthan in India.
• OD1 sense(of a pipe, tube, or shaft) Initialism of outer diameter or outside diameter.
• odd16 sensesDiffering from what is usual, ordinary or expected.
• Odd3 sensesA male given name.
• oddly2 sensesIn a peculiar manner; strangely; unusually.
• odds3 sensesThe ratio of the probability of an event happening to that of it not happening.
• Odessa17 sensesA locale in Ukraine: A port city, the administrative center of Odessa Raion and Odesa Oblast, Ukraine, situated on the northwestern shore of the…
• ODESSA1 senseA German organization founded after WWII, believed to have helped SS officers to flee from Europe.
• Odette1 senseA female given name from French.
• Odin2 sensesA major Germanic god, often described as chief of the pantheon, in his Norse form a member of the Æsir, married to Frigg and associated with…
• Odo1 senseA male given name of historical usage.
• odor4 sensesAny smell, whether fragrant or offensive.
• odyssey2 sensesAn extended adventurous voyage, usually in search of home.
• Odyssey1 senseAn Ancient Greek epic poem, ascribed to Homer, which depicts the journey of Odysseus back to Ithaca after the fall of Troy.
• of40 sensesExpressing distance or motion. Since, from (a given time, earlier state etc.).
• Of-1 senseA regulatory body for a specified industry.
• off40 sensesIn a direction away from the speaker or other reference point.
• off-limits1 senseNot to be entered or used; restricted.
• offence1 senseUK, Australia, New Zealand, and Canada standard spelling of offense.
• offend7 sensesTo hurt the feelings of; to displease; to make angry; to insult.
• offender2 sensesOne who gives or causes offense, or does something wrong.
• offense5 sensesThe act of offending. A crime or sin.
• offensive5 sensesCausing offense; arousing a visceral reaction of disgust, anger, hatred, sadness, or indignation.
• offer14 sensesA proposal that has been made.
• Offer1 senseA surname.
• offering5 sensesgerund of offer The act by which something is offered.
• office32 sensesA ceremonial duty or service, particularly
• officer7 sensesOne who has a position of authority in a hierarchical organization, especially in military, police or government organizations.
• Officer2 sensesA surname.
• official11 sensesOf or about an office or public trust.
• officially2 sensesIn an official manner; according to official rules or regulations.
• offline6 sensesOf a system, currently not connected (generally electrically) to a larger network. For example, a power plant which is not connected to the grid, or…
• offscreen3 sensesExisting or happening outside the frame of the cinema or television screen.
• offshore9 sensesMoving away from the shore.
• offspring5 sensesA person's daughter or son; a person's child.
• often2 sensesFrequently; many times on different occasions.
• Ogden15 sensesA habitational surname from Old English.
• ogre2 sensesA large, grotesque, brutish humanoid monster, typically marked by great strength and a propensity to kill or devour humans.
• Ogre1 senseA city in central Latvia.
• oh14 sensesExpression of surprise.
• Oh2 sensesA surname from Korean derived from a common Korean surname.
• OH2 sensesA hydroxyl, or alcohol, functional group.
• Ohio10 sensesA state of the United States. Capital and largest city: Columbus.
• oi6 sensesSaid to get someone's attention; hey.
• oil9 sensesLiquid fat.
• Oil2 sensesA surname from Indonesian
• oily5 sensesCovered with or containing oil.
• ointment2 sensesA viscous preparation of oils and/or fats, usually containing medication, used as a treatment or as an emollient.
• Ok1 senseA language family spoken in Papua New Guinea.
• OK14 sensesEndorsement; approval; acceptance; acquiescence.
• okey1 senseA Turkish game in which players attempt to collect certain groups of tiles.
• Okey1 senseA surname.
• Okinawa4 sensesA prefecture and island group of Japan.
• Oklahoma4 sensesA state in the central United States, formerly a territory. Capital: Oklahoma City.
• ol1 sense(attributive)
• OL2 sensesOpen line (open circuit, no continuity).
• Olaf1 senseA male given name from Old Norse.
• old21 sensesOf an object, concept, relationship, etc., having existed for a relatively long period of time.
• Old2 sensesA surname.
• old-fashioned4 sensesOf an object, outdated or no longer in vogue.
• older1 senseelderly
• Older1 senseA surname.
• oldest1 senseThe oldest child in a family, or individual in a group.
• ole1 senseAn interjection used to stir up excitement.
• Ole1 senseA male given name from Danish.
• OLE1 senseOverhead line equipment.
• Oleg1 senseA male given name from the Slavic languages.
• Olga2 sensesA female given name from Russian, Ukrainian, or Belarusian.
• olive10 sensesA tree of species Olea europaea cultivated since ancient times in the Mediterranean for its fruit and the oil obtained from it.
• Olive12 sensesA female given name from English.
• oliver1 senseA small tilt hammer, worked by the foot.
• Oliver19 sensesA male given name from the Germanic languages.
• Olivia3 sensesA female given name from Latin.
• Olivier2 sensesA surname from French, equivalent to English Oliver.
• ollie2 sensesAn aerial maneuver in which one catches air by leaping off the ground with the skateboard and into the air.
• Ollie5 sensesA unisex given name. A diminutive of the male given name Oliver, from French [in turn from Latin, in turn from Germanic].
• Olly2 sensesA diminutive of the female given name Olivia.
• Olsen1 senseA patrilineal surname.
• Olympic7 sensesOf or pertaining to the Olympic Games.
• Olympics2 sensesSynonym of Olympic Games.
• Olympus1 senseThe highest mountain in Greece; in Ancient Greek mythology the home of the gods.
• om2 sensesA sacred, mystical syllable used in prayer and meditation.
• Om1 senseA river in the south of the Western Siberian plains in Russia, a right tributary of the Irtysh.
• Omaha4 sensesA member of a tribe of Native Americans currently residing in northeastern Nebraska and western Iowa.
• omar1 senseA glacial erratic piece of (typically smooth) dark siliceous greywacke that exhibits a hemispherical pit or hole (as a result of selective…
• Omar2 sensesOmar bin al-Khattab, second Sunni Islamic caliph and a companion of Muhammad
• omega9 sensesThe twenty-fourth letter of the Classical and the Modern Greek alphabet, and the twenty-eighth letter of the Old and the Ancient Greek alphabet, i.e.…
• omelette3 sensesA dish made with beaten eggs cooked in a frying pan without stirring, flipped over to cook on both sides, and sometimes filled or topped with other…
• omen4 sensesSomething which portends or is perceived to portend either a good or evil event or circumstance in the future, or which causes a foreboding; a…
• ominous2 sensesOf or pertaining to an omen or to omens; being or exhibiting an omen; significant.
• on70 sensesIn the state of being active, functioning or operating.
• On1 senseSynonym of Heliopolis (“ancient Egyptian city”).
• on-1 senseon, at, toward, upon.
• onboard6 sensesCarried or used on or in a vehicle or vessel.
• once6 sensesOne and only one time.
• Once1 senseA fan of the Korean girl band Twice.
• one37 sensesThe number represented by the Arabic numeral 1; the numerical value equal to that cardinal number.
• one-eyed2 sensesHaving only a single eye, particularly when a greater number is normal.
• one-man1 senseInvolving, done, or operated by only one person.
• one-on-one5 sensesInvolving direct communication or competition between two people.
• one-time4 sensesOf or pertaining to a specific period of time in the past, not extending to the present.
• one-way5 sensesAllowing movement, vision, etc. in only one direction; unidirectional.
• ones2 sensesA senior or first team (as opposed to a reserves team).
• ongoing3 sensesContinuing, permanent, lasting.
• onion7 sensesA monocotyledonous plant (Allium cepa), allied to garlic, used as vegetable and spice.
• Onion1 senseAn inhabitant of Bermuda; a Bermudian.
• Onions1 senseA surname from Welsh [in turn originating as a patronymic].
• online9 sensesOf a system: connected (generally electrically) to a larger network. Of a generator or power plant: connected to the grid.
• only16 sensesAlone in a category.
• onstage2 sensesOn the part of a stage that is visible to the audience.
• onto4 sensesArriving upon or on top of (speaking of a physical or metaphorical movement).
• onward5 sensesMoving forward.
• onwards1 senseOnward.
• oo2 sensesAny of four Hawaiian birds of the genus Moho, formerly classed with the honeyeaters and now believed to be extinct.
• oof5 sensesA sound mimicking the loss of air, as if someone's solar plexus had just been struck.
• ooh8 sensesAn expression of surprise.
• ooo1 sensehugs (usually placed at the end of a letter or in text messaging, sometimes alongside xxx meaning kisses)
• oooh3 sensesElongated form of ooh.
• oop2 sensesUsed to acknowledge a small mistake or accident.
• OOP1 senseTo use object-oriented programming for a task.
• oops4 sensesUsed to acknowledge a small mistake or accident.
• op5 sensesClipping of operator. An amateur radio operator.
• open70 sensesPhysically unobstructed, uncovered, etc. Able to have something pass through or along it.
• open-minded1 senseWilling to consider new and different concepts, ideas, or opinions.
• opened1 senseHaving undergone opening.
• opener13 sensesA person who opens something.
• opening15 sensesPertaining to the start or beginning of a series of events.
• Opening1 senseSynonym of Fatiha.
• openly1 senseIn an open manner; visibly.
• opera6 sensesA theatrical work, combining drama, music, song and sometimes dance.
• operate8 sensesTo perform a work or labour; to exert power or strength, physical or mechanical; to act.
• operated2 sensesOperated by the means specified e.g. a battery-operated toy.
• operating3 sensesIn operation; that operates.
• operation10 sensesThe method by which a device performs its function.
• operational4 sensesOf or relating to operations, especially military operations.
• operations2 sensesAny practically minded combination of business administration, management science, operations research, systems engineering, and industrial…