Definition for Poison
From Biology Forums Dictionary
In the context of biology, poisons are substances that cause disturbances to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism. The fields of medicine (particularly veterinary) and zoology often distinguish a poison from a toxin, and from a venom. Toxins are poisons produced by some biological function in nature, and venoms are usually defined as toxins that are injected by a bite or sting to cause their effect, while other poisons are generally defined as substances absorbed through epithelial linings such as the skin or gut.