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a. Any of various Eurasian plants of the mustard family, especially white mustard, Indian mustard, and black mustard, which are cultivated for their pungent seeds and edible leaves.
b. A condiment made from the powdered seeds of certain of these plants.
2. A member of the mustard family.
3. A dark yellow to light olive brown.
4. Any of a group of toxic organic compounds that include mustard gas and the nitrogen mustards.
[Middle English, from Old French mustarde, from Latin mustum, must, unfermented wine; see must3.]
1. (Cookery) flavoured with mustard
2. (Cookery) resembling mustard in flavour or colour