mustard UK [ˈmʌs.təd]US /ˈmʌstəɹd/noun 8adjective 2forms 1phrases 1 noun8 •Powder or paste made from seeds of the mustard plant, and used as a condiment or a spice.When the waitress brought the food, I asked whether she had any Dijon mustard.He loved having mustard and toast for breakfast. •A plant of certain species of the genus Brassica, or of related genera (especially Sinapis alba, in the family Brassicaceae, with yellow flowers, and linear seed pods). •Dark yellow colour, the colour of mustard. •One of a family of vesicants containing one or more 2-chloroethyl (C₂H₄Cl) groups, commonly used in chemical warfare and cancer chemotherapy. •Ellipsis of mustard gas. •The leaves of the mustard plant, used as a salad.Mustard and cress sandwiches. •(informal) Energy, power (when throwing a baseball). •The tomalley of a crab, which resembles the condiment. adjective2 •Of a dark yellow colour. •(slang) Very good, or very skilled.My expectations of public services were nil, so any time within a month was fine by me. They did it in less than a week, which was mustard. — 2005 formsmustards Phrases with mustard cut the mustardTo achieve the expected standard; to be effective or good enough; to suffice.