English Words Starting With U

• uranium 239

  nounC2
  /jʊˈreɪ.ni.əm ˌtuː ˈθaʊ.zənd.ənd ˈθɜː.ti ˈnaɪn/A radioactive isotope of uranium with a mass number of 239, produced artificially and a key fissile material in nuclear reactors and weapons.
• uranium dating

  nounC2
  /jʊˈreɪ.ni.əm ˈdeɪ.tɪŋ/A radiometric dating method that calculates the age of materials by measuring the radioactive decay of uranium into lead.
• uranium dioxide

  nounC2
  /jʊˈreɪ.ni.əm daɪˈɒk.saɪd/A black, radioactive, crystalline ceramic compound composed of one uranium atom and two oxygen atoms (chemical formula UO₂).
• uranium hexafluoride

  nounC2
  /jʊˈreɪ.ni.əm ˌhek.səˈflɔː.raɪd/A chemical compound consisting of one uranium atom and six fluorine atoms (UF₆).
• uranium oxide

  nounLow
  /jʊˈreɪ.ni.əm ˈɒk.saɪd/A chemical compound consisting of uranium and oxygen.
• uranium series

  nounC1/C2
  /jʊˈreɪ.ni.əm ˈsɪə.riːz/A specific sequence of radioactive decay products, beginning with uranium-238 and ending with stable lead-206.
• uranium trioxide

  nounVery Low
  /jʊˈreɪ.ni.əm traɪˈɒk.saɪd/A chemical compound with the formula UO₃, one of the oxide forms of uranium.
• uranography

  nounC2 (Very low frequency, specialized term)
  /ˌjʊərəˈnɒɡrəfi/The branch of astronomy concerned with mapping and describing the stars, constellations, and other celestial bodies.
• uranology

  nounC2
  /ˌjʊərəˈnɒlədʒi/The scientific study of the heavens or celestial bodies; astronomy.
• uranometry

  nounVery Low (Specialized)
  /ˌjʊərəˈnɒmɪtri/The measurement of celestial positions and distances; the mapping or charting of the heavens.
• uranoscopid

  adjectivenounC2
  /jʊˌrænəˈskəʊpɪd/A fish of the Uranoscopidae family, commonly known as stargazers.
• uranus

  nounC1/C2
  /ˈjʊə.rən.əs/The seventh planet from the Sun in our solar system.
• uranyl

  nounC2
  /ˈjʊərənɪl/A bivalent ion, UO2²⁺, consisting of uranium bonded to two oxygen atoms. It is the most common and stable form of uranium in aqueous solutions and compounds.
• urartian

  adjectivenounLow
  /jʊəˈrɑːtɪən/Relating to the ancient kingdom of Urartu, located in the Armenian Highlands.
• urartu

  nounRare (C2+)
  /ʊˈrɑːtuː/The name of an ancient kingdom located in the Armenian Highlands, centred around Lake Van (modern-day eastern Turkey, Armenia, and northwestern Iran), from the 9th to 6th centuries BCE.
• urase

  nounExtremely rare / Obsolete
  /ˈjʊəreɪz/A very rare, archaic, and largely obsolete term for an enzyme that catalyzes the hydrolysis of urea into ammonia and carbon dioxide. In modern usage, it is a technical, historical, or obscure term.
• urate

  nounC2
  /ˈjʊə.reɪt/A salt or ester of uric acid, typically occurring as a sediment in urine.
• urawa

  nounExtremely low in global English; specialized/proper noun.
  /ʊˈrɑː.wə/A proper noun, specifically a place name. Refers to a major city in Saitama Prefecture, Japan.
• urb

  nounLow
  /ɜːb/A city or urban area, often used to contrast with rural or suburban areas.
• urban area

  nounC1
  /ˈɜːbən ˈeəriə/A geographic region characterized by high population density, extensive human-built infrastructure, and a concentration of economic, social, and administrative functions, typically a city or town.

Showing 1201–1220 of 1514 words.