nicotine - an alkaloid poison that occurs in tobacco; used in medicine and as an insecticidebaccy, tobacco - leaves of the tobacco plant dried and prepared for smoking or ingestion vasoconstrictive, vasoconstrictor - any agent that causes a narrowing of an opening of a blood vessel: cold or stress or nicotine or epinephrine or norepinephrine or angiotensin or vasopressin or certain drugs; maintains or increases blood pressure alkaloid - natural nitrogen-containing bases found in plants phytotoxin, plant toxin - any substance produced by plants that is similar in its properties to extracellular bacterial toxin |