[1] : 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
see also:
must brassica sinapis white mustard brassica alba black mustard 
brassica nigra wild mustard charlock brassica sinapistrum lepidium ruderale 
sisymbrium officinale thlaspi arvense arabis perfoliata erysimum cheiranthoides mustard oil 

[2] : WordNet (r) 2.0

sisymbrium officinale
     n : stiffly branching old world annual with pale yellow flowers;
         widely naturalized in north america; formerly used
         medicinally syn: hedge mustard
see also:
hedge mustard 

Sisymbrium >> S Words
Sisymbrium, definition of term: Sisymbrium
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