General English



  • A chemical element whose atomic number is 17. It is a dense and highly toxic greenish-yellow gas with a suffocating odor. It is an extremely powerful oxidizer, and is one of the most reactive elements. It has over 15 known isotopes, of which 2 are stable. Because of its activity, it does not occur uncombined in nature, although it is present in countless compounds. It has numerous applications, including its use in the preparation of chlorinated compounds used in electronics, such as carbon tetrachloride. It is a halogen, and its chemical symbol is CI.
  • chemical symbolCI


  • A highly irritant gas liberated when bleach reacts with organic matter and acids. Can be dangerous if some cleaning agents are used improperly. Used as a flour improver.

General Science

  • chemical symbolCl
    (written as Chlorine)

Information & Library Science

  • abbreviation in Internet addresses, the top-level domain for Côte d’Ivoire

Origin & History of “chlorine”

Chlorine is a greenish-yellow gas, and was named for its colour. The term was coined by the British chemist Sir Humphry Davy in 1810, from the Greek khlōrós ‘greenish-yellow’. Of other words containing this element, chlorophyll (19th c.) too was based on the notion of colour (in reference to the green colouring matter of leaves: the Greek elements literally mean ‘green leaf’), but chloroform (19th c.), originally French, is a secondary formation based ultimately on chlorine (since it was originally regarded as a trichloride of formyl).