fictional substance in the "Superman" series, where it weakens the otherwise invulnerable hero, 1943; perhaps from elements of krypton (which is a gas) + meteorite.
Entries linking to kryptonite
krypton n.
inert gaseous element, 1898, coined by its discoverers (Sir William Ramsay and Morris W. Travers) from Greek krypton, neuter of adjective kryptos "hidden" (see crypt); so called because it remained undiscovered for so long and was so difficult to find. Scientific American (July 9, 1898) announced it as "the discovery of yet another element."