• A poisonous gas that has no color or odor. It is given off by burning fuel (as in exhaust from cars or household heaters) and tobacco products. Carbon monoxide prevents red blood cells from carrying enough oxygen for cells and tissues to live.
  NCI Dictionary of Cancer Terms
  U.S. National Cancer Institute, 2021
• An odorless, colorless gas that is toxic to humans and animals at high levels; it is produced by cars, furnaces, fireplaces, and other equipment powered by combustion.
  Harvard Dictionary of Health Terms
  Harvard Medical Publishing, 2011
• An odorless, tasteless, poisonous gas, CO, that results from the incomplete combustion of carbon. Inhalation causes central nervous system damage and asphyxiation.
  NCI
  U.S. National Cancer Institute, 2021
• Carbon monoxide (CO). A poisonous colorless, odorless, tasteless gas. It combines with hemoglobin to form carboxyhemoglobin, which has no oxygen carrying capacity. The resultant oxygen deprivation causes headache, dizziness, decreased pulse and respiratory rates, unconsciousness, and death. (From Merck Index, 11th ed)
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2025
• Colorless, odorless, poisonous gas produced by incomplete fossil fuel combustion.
  CRISP Thesaurus
  National Institutes of Health, 2006