a white corrosive substance existing in three crystalline forms of which the stable (alpha-) form is usually obtained as silky needles. It is produced by the oxidation of sulphur dioxide, and is used in the sulphonation of organic compounds. Formula: SO3
Systematic name: sulphur(VI) oxide
sulfur trioxide in American English
noun
Chemistry
an irritant, corrosive, low-melting solid, SO3, obtained by the oxidation of sulfur dioxide, used as an intermediate in the manufacture of sulfuric acid
Also called: sulfuric anhydride
Word origin
[1865–70]This word is first recorded in the period 1865–70. Other words that entered Englishat around the same time include: black belt, goulash, steamroller, tick-tack-toe, valence