CAH can stand for:

• Congenital adrenal hyperplasia
• Calcium Aluminate Hydrate, an important phase in cement chemistry
• Chlorinated Aromatic Hydrocarbon
• CAH, a mnemonic used to teach trigonometry, showing that cosine is the ratio of adjacent over hypotenuse

• Cardinal Health (NYSE:CAH)
• Community of All Hallows, an Anglican religious community for women
• Capital Airport Holding, airport holdings company in the People's Republic of China
• Charlan Air Charter, a South African airline with the ICAO airline designator CAH

• Cambridge Ancient History, a bibliographic abbreviation for the work edited by Cambridge University Press
• Calvin and Hobbes, a newspaper comic strip from 1985 to 1995
• Cyanide & Happiness, a daily webcomic

• Crime against humanity
• Cards Against Humanity, a party game
• Critical Access Hospital (CAH); these must have no more than 25 beds, not counting 10 extra psychiatric beds and 10 extra inpatient rehab beds, and must be located in a rural area or an area treated as rural, be certified by the state as being a necessary provider of healthcare services to area residents, and be more than a 35-mile drive away from a hospital or other healthcare facility
• Controlled-access highway
• CAH, the IATA airport code for Cà Mau Airport