D defs.my
Entry 1 sense Webster, 1913

Trioxide

· Tri·ox·ide · IPA /trʌɪˈɒksʌɪd/
01 n. An oxide containing three atoms of oxygen; as, sulphur trioxide, SO3; -- formerly called tritoxide.
  1. 1.
    An oxide containing three atoms of oxygen; as, sulphur trioxide, SO3; -- formerly called tritoxide.(Chem.) Also: tritoxide