What is the common name for dihydrogen monoxide?

The common name for dihydrogen monoxide is water.

The formula H₂O shows why the name works: “dihydrogen” indicates two hydrogen atoms, while “monoxide” indicates one oxygen atom. Water is the everyday name used for this compound, and “dihydrogen monoxide” is an uncommon systematic-style description rather than a different substance.

The phrase became famous through the dihydrogen monoxide parody. It presents ordinary water using alarming descriptions—for example, that it can cause drowning, accelerate corrosion and occur in polluted environments—to show how technically true statements can create a misleading impression. The joke is often used to illustrate the importance of context and scientific literacy.

Water is also known by other chemical names, including oxidane, although “water” is overwhelmingly the normal term in everyday science. A water molecule contains two hydrogen atoms covalently bonded to one oxygen atom. Under ordinary conditions, water is liquid, but the same compound also appears as ice and water vapour, so the term can refer broadly to all three states.