cap·sa·i·cin (k?p-s???-s?n)n. A pungent alkaloid, C18H27NO3, derived from certain capsicums that is a strong irritant to skin and mucous membranes and is used in some topical pain relievers and in pepper sprays.[Alteration (perhaps influenced by Latin capsa, box) of earlier capsicin : capsic(um) + -in.]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.capsaicin (kæp?se??s?n) n (Biochemistry) a colourless crystalline bitter alkaloid found in capsicums and used as a flavouring in vinegar and pickles. Formula: C18H27O3N[C19 capsicine, from capsicum + -ine2; modern form refashioned from Latin capsa box, case + -in]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014cap?sa?i?cin (kæp?se? ? s?n) n. a colorless, crystalline, bitter compound, C18H27NO3, present in capsicum. [1885?90; earlier capsicine= capsic (um) + -ine2] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.