• A chemical used in manufacturing, as a bleach, and to kill bacteria and other organisms in water.
  NCI Dictionary of Cancer Terms
  U.S. National Cancer Institute, 2021
• A naturally occurring halogen element with atomic symbol Cl, atomic number 17, and atomic mass 35.453. Chlorine is used in many industrial processes, as well as in pesticides, pharmaceuticals, and water purification. It is characterized as a greenish-yellow gas with a pungent odor, and exposure occurs by inhalation, ingestion, or contact.
  NCI
  U.S. National Cancer Institute, 2021
• An element with atomic symbol Cl, atomic number 17, and atomic weight 35, and member of the halogen family.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2025
• Greenish-yellow, diatomic halogen gas element; atomic symbol Cl, atomic number 17, and atomic weight 70.906; a powerful irritant that can cause fatal pulmonary edema.
  CRISP Thesaurus
  National Institutes of Health, 2006
• The chemical agent chlorine.
  CDISC Terminology
  Clinical Data Interchange Standards Consortium (CDISC), 2021
• An element with atomic symbol Cl, atomic number 17, and atomic weight 35, and member of the halogen family.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2025