- toxin - a poisonous substance produced during the metabolism and growth of certain microorganisms and some higher plant and animal species
--1 is a kind of poison, poisonous substance
--1 has particulars:ricin, ricin toxin; animal toxin, zootoxin; bacterial toxin; cytotoxin; endotoxin; exotoxin; hepatotoxin; nephrotoxin; neurotoxin, neurolysin; plant toxin, phytotoxin