Noun
a toxic protein extracted from castor beans; used as a chemical reagent; can be used as a bioweapon
Source: WordNetone milligram of ricin can kill an adult Source: Internet
Ehrlich interpreted this as immunization and observed that it was abruptly initiated after a few days and was still in existence after several months, but mice immunized against ricin were just as sensitive to abrin as untreated animals. Source: Internet
In August 1971 the KGB allegedly made an attempt to assassinate Solzhenitsyn using an unknown biological agent (most likely ricin ) with an experimental gel-based delivery method. Source: Internet
Note that two of these targets are toxins (botulinum and ricin) while the remainder are infectious agents. Source: Internet