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 ]