English Words Starting With O

• oppilate

  verbverb-transitiveExtremely rare/obsolete
  /ˈɒpɪleɪt/To block or obstruct a passage, especially in a bodily duct or vessel.
• oppo

  nounB2
  /ˈɒp.əʊ/A short, informal term for 'opponent', 'opposition', or 'opportunity', most commonly used in British English to mean a work colleague or friend, especially of equal rank.
• opponency

  nounVery Low (C2)
  /əˈpəʊnənsi/The state, condition, or quality of being an opponent or opposed; opposition.
• opponent

  adjectivenounB2 (Upper Intermediate)
  /əˈpəʊnənt/A person who competes against or fights another in a contest, game, or argument; a person who disagrees with or resists a proposal, idea, or system.
• opportunism

  nounC1-C2
  /ˌɒp.əˈtjuː.nɪ.zəm/The practice of taking advantage of situations for personal gain, often with little regard for principles or consequences.
• opportunist

  adjectivenounC1
  /ˌɒp.əˈtʃuː.nɪst/A person who takes advantage of opportunities as they arise, especially with little regard for principles or consequences.
• opportunity

  nounB1
  /ˌɒp.əˈtjuː.nə.ti/A favourable or advantageous combination of circumstances; a chance or opening for action or advancement.
• opportunity cost

  nounB2
  /ˌɒp.əˌtjuː.nə.ti ˈkɒst/The value of the best alternative forgone when a specific choice is made.
• opportunity shop

  nounMedium
  /ˌɒp.əˈtʃuː.nə.ti ˌʃɒp/A shop, typically run by a charity, where second-hand goods are sold to raise money for that charity.
• oppose

  verbverb-intransitiveverb-transitiveB2
  /əˈpəʊz/To actively disagree with or resist something or someone; to set oneself in direct contrast to.
• opposed

  adjectiveverbC1
  /əˈpəʊzd/Actively resisting, arguing against, or standing in contrast to something.
• opposed-piston engine

  nounVery Low
  /əˈpəʊzd ˈpɪstən ˈɛndʒɪn/An internal combustion engine design where two pistons are arranged in a single cylinder, moving in opposite directions towards each other, with combustion occurring between them.
• opposite

  adjectiveadverbnounprepositionB1
  /ˈɒpəzɪt/Situated directly across from something else; facing.
• opposite field

  nounC1
  /ˈɒpəzɪt fiːld/In baseball/softball, the area of the outfield that is opposite to the batter's natural hitting side (e.g., right field for a left-handed batter).
• opposite number

  nounC1/C2
  /ˌɒp.ə.zɪt ˈnʌm.bər/A person who holds the same position or fulfills the same function in a different organization, group, or team; a counterpart.
• opposite prompt

  nounVery Low
  /ˈɒpəzɪt prɒmpt/A term from AI/ML referring to an input designed to generate content contrary to or reversing the typical output of a model.
• opposite sex

  adjectivenounC1
  /ˈɒpəzɪt sɛks/The other of the two conventional sexes or genders (men relative to women, or women relative to men), used primarily in the context of biological and social differences.
• opposition

  nounB2
  /ˌɒp.əˈzɪʃ.ən/The state of disagreeing with or resisting someone or something; active or passive resistance or disagreement.
• opposition research

  nounB2
  /ˌɒpəˈzɪʃən rɪˈsɜːtʃ/The systematic collection and analysis of information about a political opponent or rival party, typically with the aim of finding damaging information to use against them in a campaign.
• oppositional defiant disorder

  nounLow
  /ˌɒp.əˈzɪʃ.ən.əl dɪˈfaɪənt dɪsˈɔː.dər/A childhood behavioral disorder characterized by a persistent pattern of angry, defiant, argumentative, and vindictive behavior toward authority figures.

Showing 1521–1540 of 3187 words.