Definition of oleum in English:

oleum

Pronunciation /ˈōlēəm/ /ˈoʊliəm/

noun

  • A dense, corrosive liquid consisting of concentrated sulfuric acid containing excess sulfur trioxide in solution.

    • ‘In Tennessee all officers undergo training in which they are exposed to both CS and oleum capsicum, and no significant injuries from exposure have been reported.’

Origin

Early 20th century from Latin, literally ‘oil’.