noun

1. any of several annual herbs (genus Brassica) of the crucifer family, with yellow flowers and slender pods containing round seeds
2. the ground or powdered seeds of some species (as Brassica nigra) of these plants, often prepared as a paste, used as a pungent seasoning for foods, or as a counterirritant in medicine
3. the color of ground mustard, a dark yellow

Etymology: ME mustarde < OFr moustarde < moust, must < L mustum (see must): orig. prepared with must as an ingredient