a common nonmetallic element belonging to the halogens; best known as a heavy yellow irritating toxic gas; used to purify water and as a bleaching agent and disinfectant; occurs naturally only as a salt (as in sea water)
"The swimming pool turned green because someone forgot to add enough chlorine to kill the algae."
A toxic, green, gaseous chemical element (symbol Cl) with an atomic number of 17.
"The leak released a thick cloud of chlorine gas that forced everyone to evacuate the building immediately."
British chemist Humphry Davy coined the name chlorine in 1810 by combining the Ancient Greek word for "pale green" with a suffix. The term was chosen to describe the element's distinctive pale green color.