English Words Starting With U

• ultramontanism

  nounVery Low
  /ˌʌl.trəˈmɒn.tə.nɪ.zəm/The policy of advocating supreme papal authority in matters of faith and discipline, and in politics where applicable.
• ultranationalism

  nounC2
  /ˌʌltrəˈnæʃnəlɪzəm/An extreme form of nationalism that advocates aggressive and expansionist policies, often with a sense of superiority over other nations.
• ultranationalist

  adjectivenounC2
  /ˌʌl.trəˈnæʃ.nə.lɪst/A person who holds extreme, radical, or fanatical nationalist views, often advocating for the supremacy of their own nation over others.
• ultranet

  nounExtremely rare / Technical
  /ˈʌl.trə.net/A hypothetical or specialized network operating at extremely high speeds or with advanced capabilities beyond conventional networks.
• ultrared

  adjectivenounVery Low (obsolete/technical)
  /ˌʌl.trəˈred/A rarely used, somewhat archaic or technical term for 'infrared'—radiation with wavelengths just longer than those of visible red light.
• ultraright

  adjectivenounLow
  /ˌʌl.trəˈraɪt/Extreme right-wing in political ideology; far beyond mainstream conservative positions.
• ultrarightist

  adjectivenounLow
  /ˌʌl.trəˈraɪ.tɪst/A person who holds extremely conservative or reactionary political views, often associated with authoritarianism, nationalism, or opposition to liberal democracy.
• ultrasonic cleaning

  nounLow in everyday language, but high in technical and industrial contexts.
  /ˌʌltrəˈsɒnɪk ˈkliːnɪŋ/A cleaning process that uses high-frequency sound waves (typically 20–400 kHz) to agitate a fluid, creating cavitation bubbles that implode and remove contaminants from surfaces.
• ultrasonic testing

  nounLow
  /ˌʌltrəˈsɒnɪk ˈtestɪŋ/A non-destructive testing method that uses high-frequency sound waves above the range of human hearing to detect flaws, measure thickness, or characterize materials.
• ultrasonic welding

  nounLow
  /ˌʌl.trəˈsɒn.ɪk ˈwel.dɪŋ/An industrial welding technique that uses high-frequency ultrasonic vibrations to join materials, typically plastics or thin metals, without melting them.
• ultrasonics

  nounC2
  /ˌʌl.trəˈsɒn.ɪks/The branch of acoustics dealing with sound waves at frequencies above the upper limit of human hearing (generally above 20 kHz).
• ultrasonography

  nounC2
  /ˌʌl.trə.səˈnɒɡ.rə.fi/A medical diagnostic technique that uses high-frequency sound waves to produce images of structures within the body.
• ultrasound

  nounB2
  /ˈʌl.trə.saʊnd/Sound waves with a frequency higher than the upper limit of human hearing, used especially in medical imaging and some therapies.
• ultrasound scanner

  nounB2
  /ˈʌltrəsaʊnd ˈskænə(r)/A medical device that uses high-frequency sound waves to produce images of internal body structures, primarily used for diagnostic purposes and monitoring pregnancies.
• ultrastructure

  nounC1
  /ˈʌl.trəˌstrʌk.tʃər/The detailed structure of a biological specimen (e.g., a cell, organelle, or tissue) as visible with an electron microscope, showing features beyond the resolution of a light microscope.
• ultraviolet

  adjectivenounB2
  /ˌʌl.trəˈvaɪə.lət/Referring to electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays.
• ultraviolet astronomy

  nounRare/Very Low
  /ˌʌl.trə.vaɪə.lət əˈstrɒn.ə.mi/The branch of astronomy that studies celestial objects and phenomena in the ultraviolet portion of the electromagnetic spectrum.
• ultraviolet filter

  nounC1
  /ˌʌl.trəˈvaɪə.lət ˈfɪl.tə(r)/A device or substance that blocks or absorbs ultraviolet (UV) radiation.
• ultravirus

  nounExtremely Rare
  /ˈʌl.trəˌvaɪ.rəs/A virus so small it passes through filters that retain ordinary bacteria; a filterable virus.
• ultrawideband

  nounLow
  /ˌʌltrəˌwaɪdˈbænd/A radio technology that uses a very low energy level for short-range, high-bandwidth communications over a wide spectrum of frequencies.

Showing 161–180 of 1514 words.