Source : Webster's Revised Unabridged Dictionary (1913)

Sinigrin \Sin"i*grin\, n. [From NL. Sinapis nigra.] (Chem.)
   A glucoside found in the seeds of black mustard ({Brassica
   nigra}, formerly {Sinapis nigra}) It resembles sinalbin, and
   consists of a potassium salt of myronic acid.

Source : WordNet®

Brassica nigra
     n : widespread Eurasian annual plant cultivated for its pungent
         seeds; a principal source of table mustard [syn: {black
         mustard}]