Mustard

n.
  1. (Bot.) The name of several cruciferous plants of the genus Brassica (formerly Sinapis), as white mustard (Brassica alba), black mustard (Brassica Nigra), wild mustard or charlock (Brassica Sinapistrum).
  2. A powder or a paste made from the seeds of black or white mustard, used as a condiment and a rubefacient. Taken internally it is stimulant and diuretic, and in large doses is emetic.
    3. Mustard oil (Chem.),
    a substance obtained from mustard, as a transparent, volatile and intensely pungent oil. The name is also extended to a number of analogous compounds produced either naturally or artificially.