English Words Starting With H

• hydroxyl group

  nounTechnical / C1+
  /haɪˌdrɒk.sɪl ˈɡruːp/A functional group consisting of one oxygen atom covalently bonded to one hydrogen atom (-OH), present in alcohols, phenols, and carboxylic acids.
• hydroxylamine

  nounVery Low
  /haɪˌdrɒks.ɪl.əˈmiːn/An inorganic compound with the formula NH₂OH, consisting of a hydroxyl group attached to an amine group.
• hydroxylase

  nounVery Low
  /haɪˈdrɒksɪleɪz/An enzyme that catalyzes the introduction of a hydroxyl group (-OH) into an organic molecule.
• hydroxylate

  verb-transitiveC2 (Very low frequency, highly specialized)
  /haɪˈdrɒksɪleɪt/To introduce a hydroxyl group (-OH) into a compound.
• hydroxynaphthalene

  nounC2
  /haɪˌdrɒksɪˈnæfθəliːn/A class of organic compounds consisting of a naphthalene ring system (a fused pair of benzene rings) with one or more hydroxyl (-OH) groups attached.
• hydroxyproline

  nounC2
  /haɪˌdrɒksɪˈprəʊliːn/A modified amino acid found in collagen and other proteins, formed by the hydroxylation of proline.
• hydroxytryptamine

  nounVery Low
  /haɪˌdrɒk.sɪˈtrɪp.tə.miːn/A type of chemical neurotransmitter derived from tryptamine, most commonly referring to serotonin.
• hydroxyurea

  nounC2 (Specialized/Technical)
  /haɪˌdrɒks.i.jʊˈriː.ə/A chemotherapeutic agent used to treat certain cancers and sickle cell disease, functioning as an antimetabolite that inhibits DNA synthesis.
• hydroxyzine

  nounLow
  /haɪˈdrɒksɪziːn/A prescription antihistamine medication used primarily to treat anxiety, tension, and allergic skin reactions.
• hydrozincite

  nounVery Low (Technical/Scientific)
  /ˌhaɪ.drəʊˈzɪŋ.kaɪt/A secondary zinc carbonate hydroxide mineral, typically found in oxidation zones of zinc ore deposits, often appearing as white, grey, or yellowish earthy masses or crusts.
• hydrozoan

  adjectivenounC2
  /ˌhaɪ.drəˈzəʊ.ən/A member of a class (Hydrozoa) of aquatic, mostly marine, cnidarian animals, many of which have both polyp and medusa stages in their life cycle.
• hydrus

  nounVery Low
  /ˈhʌɪdrəs/A constellation in the southern hemisphere, named after a mythical water serpent.
• hyena

  nounB2
  /haɪˈiː.nə/A carnivorous mammal of Africa and Asia, known for its dog-like appearance, powerful jaws, scavenging behaviour, and distinctive laughing or cackling vocalisation.
• hyeres

  nounLow (primarily in geographical, travel, and historical contexts)
  /ˈjɛər/A town in southeastern France, on the French Riviera, known for its historic center, palm trees, and nearby islands.
• hyetograph

  nounVery Low
  /ˈhaɪ.ɪ.tə.ɡrɑːf/A chart or graph showing the distribution of rainfall over a specific area and period.
• hyetography

  nounExtremely low (technical/scientific term)
  /ˌhaɪ.ɪˈtɒɡ.rə.fi/The scientific description and analysis of rainfall patterns and distribution.
• hyetology

  nounRare / Scientific / C2+
  /ˌhaɪ.ɪˈtɒl.ə.dʒi/The scientific study of precipitation, especially rainfall.
• hygeia

  nounRare
  /haɪˈdʒiːə/The ancient Greek goddess of health, cleanliness, and hygiene.
• hygge

  adjectivenounLow-to-medium
  /ˈhʊɡ.ə/A Danish and Norwegian concept describing a quality of cosiness, comfortable conviviality, and contentment often associated with simple, pleasant, and reassuring moments, particularly in one's home or with close company.
• hygieia

  nounVery low
  /hʌɪˈdʒiːə/The Greek goddess of health, cleanliness, and sanitation.

Showing 5581–5600 of 5990 words.