English Words Starting With H

• hydrosulphurous acid

  nounExtremely Low (Academic/Specialist Historical)
  /ˌhaɪ.drəʊ.ˌsʌl.ˈfjʊə.rəs ˈæs.ɪd/A theoretical or historical chemical name referring to an oxyacid of sulfur in a lower oxidation state, specifically thiosulfuric acid (H₂S₂O₃).
• hydrotaxis

  nounVery Low
  /ˌhaɪ.drəʊˈtæk.sɪs/The movement of an organism or cell in response to moisture or water.
• hydrotheca

  nounVery Low
  /ˌhaɪdrə(ʊ)ˈθiːkə/A protective sheath or skeletal cup that houses individual hydranths (feeding polyps) in a colonial hydroid.
• hydrotherapeutics

  nounVery Low
  /ˌhaɪ.drəʊ.θer.əˈpjuː.tɪks/The treatment of disease or injury by the external application of water, usually in specific forms and temperatures.
• hydrotherapy

  nounLow
  /ˌhaɪ.drəʊˈθer.ə.pi/A therapeutic method that uses water for treating various conditions.
• hydrothermal vent

  nounLow
  /ˌhaɪ.drəʊˈθɜː.məl ˈvent/A fissure on the seafloor from which geothermally heated mineral-rich water discharges.
• hydrothorax

  nounVery Low (C2+)
  /ˌhaɪ.drəʊˈθɔː.ræks/A pathological accumulation of fluid (hydro) in the pleural cavity (thorax).
• hydrotropism

  nounRare
  /haɪˈdrɒ.trə.pɪ.zəm/A biological phenomenon where a plant's roots grow towards moisture in the soil.
• hydrovane

  nounVery Low
  /ˈhaɪ.drəʊ.veɪn/A control surface, typically on a ship or submarine, that uses the flow of water to help steer or stabilize the vessel.
• hydroxide

  nounLow in everyday conversation; Very High in scientific/technical contexts.
  /haɪˈdrɒk.saɪd/A chemical compound consisting of one oxygen atom and one hydrogen atom bonded together and carrying a negative electric charge (OH⁻), or any compound containing this group, typically a base.
• hydroxide ion

  nounVery Low (Academic/Technical)
  /haɪˈdrɒk.saɪd ˌaɪ.ən/A negatively charged ion (anion) consisting of one oxygen atom and one hydrogen atom, with the chemical formula OH⁻.
• hydroxonium ion

  nounC2/Highly Technical
  /haɪˌdrɒkˈsəʊ.ni.əm ˈaɪ.ən/The positively charged ion H₃O⁺, formed by the association of a proton (H⁺) with a water molecule.
• hydroxy acid

  nounC1
  /haɪˌdrɒk.si ˈæs.ɪd/A type of acid that contains a hydroxyl group within its molecular structure.
• hydroxyacetic acid

  nounC2
  /haɪˌdrɒks.i.əˈsiːtɪk ˈæsɪd/A simple organic acid with the chemical formula C₂H₄O₃, containing both a hydroxyl (-OH) and a carboxylic acid (-COOH) group.
• hydroxyapatite

  nounC2/Technical
  /haɪˌdrɒksɪˈæpətaɪt/A calcium phosphate mineral that is the primary inorganic constituent of bone and tooth enamel.
• hydroxybenzene

  nounLow (Technical/Scientific)
  /haɪˌdrɒksɪˈbɛnziːn/An aromatic organic compound consisting of a benzene ring with one hydrogen atom replaced by a hydroxyl group; the systematic name for phenol.
• hydroxybutyric acid

  nounVery Low
  /haɪˌdrɒksɪbjuːˈtɪrɪk ˈæsɪd/a four-carbon carboxylic acid with a hydroxyl group, notable as a ketone body produced during fatty acid metabolism.
• hydroxychloroquine

  nounLow frequency (C1/C2). Specialized/technical term with spikes in general usage during news events.
  /ˌhaɪ.drɒk.siˈklɔː.rə.kwiːn/A medication primarily used to prevent and treat malaria, and to treat autoimmune conditions like rheumatoid arthritis and lupus.
• hydroxyketone

  nounVery Low / Technical
  /haɪˌdrɒk.siˈkiː.təʊn/An organic compound containing both a hydroxyl group (-OH) and a ketone group (C=O) within the same molecule.
• hydroxyl

  adjectivenounC2
  /haɪˈdrɒksɪl/A chemical group consisting of one oxygen atom and one hydrogen atom bonded together (‑OH), which is characteristic of alcohols and many other organic compounds.

Showing 5561–5580 of 5990 words.