Advanced Vocabulary Starting with "O"

81 entries

• obdurate Stubbornly refusing to change one's opinion or course of action despite attem...
• obfuscate To make something unclear, obscure, or unintelligible, especially deliberatel...
• obfuscation The deliberate act of making something unclear, confusing, or difficult to un...
• objectively In a way that is not influenced by personal feelings, interpretations, or pre...
• objectivity The quality of being based on facts and free from personal feelings, interpre...
• oblique Not direct or straightforward; approaching a subject indirectly or at an angl...
• obliterate To destroy utterly, leaving no trace; to remove all signs of something comple...
• oblivious Entirely unaware of or inattentive to what is happening around one, often to ...
• obscure Not well known, or difficult to understand or perceive clearly; as a verb, to...
• obsequious Excessively eager to please or obey, especially in order to gain favour from ...
• obsolescent In the process of becoming obsolete; going out of use or becoming outdated.
• obsolete No longer in use or no longer useful; outdated and replaced by something newe...
• obstacle A thing that blocks one's way or prevents or hinders progress.
• obstinate Stubbornly refusing to change one's opinion or course of action despite persu...
• obstreperous Noisy, unruly, and difficult to control. Describes boisterous or aggressively...
• obtuse Annoyingly slow to understand or perceive something; lacking sharpness of min...
• obverse The front or principal side of something, especially a coin or medal. More br...
• obviate To remove or prevent a difficulty or disadvantage, making a particular course...
• odious Extremely unpleasant or repulsive, inspiring hatred or disgust. A strong term...
• oedema An abnormal accumulation of fluid in the body's tissues, causing swelling. Th...
• officious Asserting authority or interfering in a domineering way, especially regarding...
• oligarchic Relating to or characteristic of an oligarchy, a form of government in which ...
• oligarchy A form of government in which power is held by a small group of people, typic...
• oligopoly A market structure in which a small number of firms dominate the industry, of...
• ombudsman An independent official appointed to investigate complaints by individuals ag...
• ominous Giving the impression that something bad or unpleasant is about to happen; th...
• omnibus A volume containing several works previously published separately, or an adje...
• omnivore An animal that eats food of both plant and animal origin.
• oncology The branch of medicine that deals with the prevention, diagnosis, and treatme...
• onerous Involving heavy obligations or responsibilities; burdensome and demanding con...
• onlooker A person who watches something happening without becoming involved, typically...
• onomatopoeia The formation of a word that imitates or suggests the natural sound associate...
• ontology The branch of philosophy that studies the fundamental nature of being, existe...
• opaque Not able to be seen through; not transparent. Figuratively: difficult to unde...
• operational Relating to the routine functioning or active operations of an organisation, ...
• ophthalmology The branch of medicine concerned with the study, diagnosis, and treatment of ...
• opportunistic Exploiting circumstances or chances as they arise, often with little regard f...
• oppressive Unjustly harsh, burdensome, or authoritarian; weighing heavily on people's fr...
• opprobrious Expressing scorn, contempt, or harsh criticism. Describes language, behaviour...
• optic Relating to the eye or to the science of vision and light. Also used as a nou...
• optimise To make the best or most effective use of a situation, resource, or system; t...
• optimism Hopefulness and confidence about the future or the successful outcome of some...
• optimist A person who tends to expect favourable outcomes and sees the positive side o...
• opulent Ostentatiously rich and luxurious; displaying great wealth.
• opus A musical composition or set of compositions numbered as one of a composer's ...
• oracular Resembling an oracle in authority or obscurity; making pronouncements as if d...
• oratory The art or practice of formal public speaking, particularly when eloquent, pe...
• orbit The curved path of a celestial body or spacecraft around a star, planet, or o...
• orbital Relating to an orbit, whether of a celestial body, a satellite, or an electro...
• ordain To officially confer holy orders on someone, making them a priest or minister...
• ordinance An authoritative decree or law, especially one enacted by a local authority o...
• organisational Relating to the way in which something is organised, structured, or managed; ...
• ornate Elaborately or excessively decorated; highly embellished. Used of architectur...
• orthodox Conforming to what is generally or traditionally accepted as right or true; f...
• orthogonal At right angles to one another, or in broader technical usage, describing thi...
• orthopaedic Relating to the branch of medicine dealing with the correction or prevention ...
• orthosis An externally applied medical device used to support, align, or correct the f...
• oscillate To swing or fluctuate regularly between two states, positions, or extremes, w...
• oscillation A repetitive back-and-forth movement or fluctuation between two states, value...
• oscillator A device or circuit that produces a repetitive, alternating signal — typicall...
• oscilloscope An electronic instrument that displays varying electrical signals as a wavefo...
• osmose To pass gradually or be absorbed as if by osmosis — the slow, almost unconsci...
• osmosis The movement of water or another solvent through a semipermeable membrane fro...
• ostensible Stated or appearing to be true, but not necessarily so; seeming or professed ...
• ostensibly As appears or is stated to be true, though not necessarily so; seemingly, wit...
• ostentatious Designed to impress or attract notice; characterized by vulgar or pretentious...
• ostracism Exclusion from a group or society by common consent; the deliberate shunning ...
• outcast A person who has been rejected or excluded from a social group or community; ...
• outlier A data point, person, or thing that differs significantly from the rest of a ...
• outpatient A patient who attends a hospital or clinic for treatment without being admitt...
• outsource To contract out business processes or functions to an external provider, ofte...
• overhaul A thorough examination and repair of a system, machine, or process; as a verb...
• overhead The ongoing costs of running a business that are not directly attributable to...
• overshoot The extent to which a system's response exceeds its intended target or set po...
• oversight An unintentional failure to notice or do something; alternatively, the superv...
• overt Done or shown openly and without any attempt at concealment; plainly apparent.
• overtone A higher-frequency component of a complex sound wave that accompanies the fun...
• overture An orchestral composition played as an introduction to an opera, ballet, or m...
• oxidation A chemical reaction in which a substance combines with oxygen or loses electr...
• oxymoron A figure of speech in which two apparently contradictory terms are combined t...
• ozone A form of oxygen with three atoms per molecule (O3), found naturally in the E...