1. 1. Any of various Eurasian plants of the genus Brassica, especially B. nigra and B. juncea, which are cultivated for their pungent seeds and edible leaves.
   2. 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.

[Middle English, from Old French mustarde, from Latin mustum, must, unfermented wine. See must³.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.