n. [ L. ricinus castor-oil plant. ] (Chem.) A bitter white crystalline alkaloid (C8H8N2O2) extracted from the seeds of the castor-oil plant (Ricinus communalis). Called also ricidine. Ingestion may cause vomiting and various other toxic reactions, including liver and kidney damage, convulsions, hypotension, and death. [ 1913 Webster +PJC ]