The systematic names for water, as determined by the International Union of Pure and Applied Chemistry (IUPAC), are water and oxidane, although water is the more commonly used term by chemists. The traditional name has been retained for ease of communication.
There are other ways of expressing the idea of water and its molecular structure, but they are not endorsed by the IUPAC. The terms dihydrogen monoxide and DHMO have been used in several hoaxes on the public to stress the dangers of water and make it sound like a strange and toxic chemical. One of the earliest examples is an email dating from 1997 calling for a ban on dihydrogen monoxide. The same email claims that dihydrogen monoxide is also called hydroxyl acid. One of the ACD/Index names for water is, indeed, hydroxyl, although it is not specified as an acid. Other names for water used by chemists include hydrogen hydroxide, hydrogen oxide and more familiar terms such as ice or water vapor.