A volatile oil obtained from crushed seeds of black mustard, used medicinally as a counterirritant; (Chemistry) allyl isothiocyanate, the chief component of this oil, or a structurally related compound.
Origin
Mid 19th century; earliest use found in George Fownes (1815–1849), chemist.
Definition of mustard oil in US English:
mustard oil
noun
A volatile oil obtained from crushed seeds of black mustard, used medicinally as a counterirritant; (Chemistry) allyl isothiocyanate, the chief component of this oil, or a structurally related compound.
Origin
Mid 19th century; earliest use found in George Fownes (1815–1849), chemist.