Definition of oleum in English:

oleum

noun

  • [mass noun] A dense, corrosive liquid consisting of concentrated sulphuric acid containing excess sulphur 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.

Pronunciation:

oleum

/ˈəʊlɪəm/