Water is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent). It is vital for all known forms of life, even though it provides no calories or organic nutrients.

The dihydrogen monoxide parody involves calling water by an unfamiliar chemical name, most often "dihydrogen monoxide" (DHMO), and listing some of water's properties in a particularly alarming manner, such as accelerating corrosion (rust) and causing suffocation (drowning). The parody often calls for dihydrogen monoxide to be banned, regulated, or labeled as dangerous. It plays into chemophobia and demonstrates how a lack of scientific literacy and an exaggerated analysis can lead to misplaced fears. The parody has been used with other chemical names such as hydrogen hydroxide, dihydrogen oxide and hydroxic acid.

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