inert gases

Main Entry: no·ble gas
Pronunciation: 'nO-b&l-
Function: noun
: any of a group of rare gases that include helium, neon, argon, krypton, xenon, andsometimes radon and that exhibit great stability and extremely low reaction rates called also inert gas

noble gas no·ble gas (nō'bəl)
n.
Any of the elements in Group O of the periodic table, including helium, neon, argon, krypton, xenon, and radon, which are monatomic and with limited exceptions chemically inert. Also called inert gas.