A colorless gaseous substance (O/) obtained (as by the
   silent discharge of electricity in oxygen) as an allotropic form of
   oxygen, containing three atoms in the molecule. It is a streng
   oxidizer, and probably exists in the air, though by he ordinary tests
   it is liable to be confused with certain other substances, as hydrogen
   dioxide, or certain oxides of nitrogen. It derives its name from its
   peculiar odor, which resembles that of weak chlorine.