noun 1.a pungent powder or paste prepared from the seed of the mustard plant, used as a food seasoning or condiment, and medicinally in plasters, poultices, etc.
2.any of various acrid or pungent plants, especially of the genus
Brassica, as
B. juncea (leaf mustard), the leaves of
which are used for food and
B. nigra (black mustard), the chief source of commercial mustard, and
Sinapis alba (white mustard). Compare mustard family. Idiom4.cut the mustard, Slang. to reach or surpass the desired standard of performance: a pitcher who cuts the mustard with his fastball.