a rare, gaseous chemical element, one of the noble gases, present in very small quantities in air: basically inert, it reacts with fluorine and some other elements under special conditions: symbol, Kr; at. no., 36
See krypton in American Heritage Dictionary 4
(krĭpˈtŏnˌ)
noun Symbol Kr
A whitish, largely inert gaseous element used chiefly in gas discharge lamps and fluorescent lamps. Atomic number 36; atomic weight 83.80; melting point -156.6°C; boiling point -152.30°C; density 3.73 grams per liter (0°C). See Table at element.