from
The Collaborative International Dictionary of English v.0.48
Mustard \Mus"tard\, n. [OF. moustarde, F. moutarde, fr. L.
mustum must, -- mustard was prepared for use by being mixed
with must. See {Must}, n.]
1. (Bot.) The name of several cruciferous plants of the genus
{Brassica} (formerly {Sinapis}), as {white mustard}
({Brassica alba}), {black mustard} ({Brassica Nigra}),
{wild mustard} or {charlock} ({Brassica Sinapistrum}).
[1913 Webster]
Note: There are also many herbs of the same family which are
called mustard, and have more or less of the flavor of
the true mustard; as, bowyer's mustard ({Lepidium
ruderale}); hedge mustard ({Sisymbrium officinale});
Mithridate mustard ({Thlaspi arvense}); tower mustard
({Arabis perfoliata}); treacle mustard ({Erysimum
cheiranthoides}).
[1913 Webster]
2. A powder or a paste made from the seeds of black or white
mustard, used as a condiment and a rubefacient. Taken
internally it is stimulant and diuretic, and in large
doses is emetic.
[1913 Webster]
{Mustard oil} (Chem.), a substance obtained from mustard, as
a transparent, volatile and intensely pungent oil. The
name is also extended to a number of analogous compounds
produced either naturally or artificially.
[1913 Webster]