English Words Starting With O

• oscar ii

  nounC2
  /ˌɒskə(r) ðə ˈsekənd/The proper name of a historical monarch, King Oscar II of Sweden and Norway (1829-1907).
• osceola

  nounLow
  /ˌɒsiːˈəʊlə/The name of a prominent 19th-century Seminole leader.
• oscillate

  verbverb-intransitiveverb-transitiveC1
  /ˈɒs.ɪ.leɪt/To swing or move back and forth in a regular rhythm, like a pendulum.
• oscillating circuit

  nounC2
  /ˈɒs.ɪ.leɪ.tɪŋ ˈsɜː.kɪt/A closed electrical circuit designed to generate a continuous, repeating waveform (e.g., sine wave) without an external signal source.
• oscillating engine

  nounC2
  /ˈɒs.ɪ.leɪ.tɪŋ ˈen.dʒɪn/A steam engine in which the entire cylinder assembly rocks (oscillates) on trunnions to operate the valve and connect to the crankshaft, eliminating the need for a separate connecting rod mechanism.
• oscillating universe

  nounC2
  /ˈɒs.ɪ.leɪ.tɪŋ ˈjuː.nɪ.vɜːs/A cosmological model in which the universe undergoes repeated cycles of expansion and contraction.
• oscillating universe theory

  nounVery Low
  /ˈɒs.ɪ.leɪ.tɪŋ ˈjuː.nɪ.vɜːs ˈθɪə.ri/A cosmological model proposing the universe undergoes infinite, sequential cycles of expansion (a Big Bang) followed by contraction (a Big Crunch).
• oscillation

  nounC1
  /ˌɒsɪˈleɪʃən/A regular back-and-forth movement or variation between two states, positions, or opinions.
• oscillator

  nounC1
  /ˈɒs.ɪ.leɪ.tə/A device or circuit that generates a periodic, repeating electronic signal.
• oscillogram

  nounC2 / Very Low
  /əˈsɪlə(ʊ)ɡram/A visual record or graph produced by an oscilloscope, showing changes in an electrical quantity over time.
• oscillograph

  nounC2
  /əˈsɪləɡrɑːf/An instrument for recording oscillations, especially electrical oscillations, as a continuous graph.
• oscillometer

  nounVery Low (Specialist Technical Term)
  /ˌɒsɪˈlɒmɪtə/An instrument for measuring oscillations or vibrations.
• oscilloscope

  nounC2
  /əˈsɪləskəʊp/An electronic test instrument that displays the varying voltage of an electrical signal as a two-dimensional plot over time.
• oscine

  adjectivenounC2/Rare
  /ˈɒsaɪn/A member of the suborder Oscines of passerine birds, known for their complex vocal organs and ability to produce elaborate songs.
• oscitancy

  nounExtremely rare / Obsolete
  /ˈɒsɪt(ə)nsi/The act of yawning; sleepiness or drowsiness.
• osco-umbrian

  adjectivenounRare (C2 Level). Primarily encountered in specialized academic texts on ancient Italy, Indo-European linguistics, or Roman history.
  /ˌɒskəʊˈʌmbriən/A group of closely related Italic languages, including Oscan and Umbrian, spoken in central and southern Italy before Roman dominance.
• osculate

  verbverb-intransitiveverb-transitiveC2
  /ˈɒskjʊleɪt/To kiss, especially in a formal or ceremonial manner.
• osculating circle

  nounVery low
  /ˈɒs.kjʊ.leɪ.tɪŋ ˈsɜː.kəl/In geometry, the circle that most closely approximates a curve at a given point, having the same tangent and curvature at that point.
• osculating plane

  nounVery Low
  /ˈɒskjʊleɪtɪŋ pleɪn/In differential geometry, the plane that most closely approximates a curve at a given point, containing the tangent and normal vectors.
• osculation

  nounC2
  /ˌɒskjʊˈleɪʃ(ə)n/The act of kissing.

Showing 2141–2160 of 3187 words.