a. (Chem.) Of or pertaining to sinapine; specifically, designating an acid (C11H12O5) related to gallic acid, and obtained by the decomposition of sinapine, as a white crystalline substance. [ 1913 Webster ]

n. [ L. sinapi, sinapis, mustard, Gr. &unr_;&unr_;&unr_;: cf. F. sinapine. ] (Chem.) An alkaloid occuring in the seeds of mustard. It is extracted, in combination with sulphocyanic acid, as a white crystalline substance, having a hot, bitter taste. When sinapine is isolated it is unstable and undergoes decomposition. [ 1913 Webster ]

‖n. [ L. ] (Bot.) A disused generic name for mustard; -- now called Brassica. [ 1913 Webster ]

n. (Chem.) A substance extracted from mustard seed and probably identical with sinalbin. [ Obs. ] [ 1913 Webster ]

n. [ L. sinapismus, Gr. &unr_;&unr_;&unr_;&unr_;, the use of a mustard blister, fr. &unr_;&unr_;&unr_; to apply a mustard blister, fr. &unr_;&unr_;&unr_;&unr_; mustard. ] (Med.) A plaster or poultice composed principally of powdered mustard seed, or containing the volatile oil of mustard seed. It is a powerful irritant. [ 1913 Webster ]