ricin

/ˈraɪsɪn/
noun
  1. A highly poisonous substance found in castor beans, which can be made into a powder or mist and is dangerous if inhaled, swallowed, or injected.
    • Scientists study ricin to understand how it attacks cells and to develop antidotes.
    • Because ricin is so toxic, it is classified as a potential biological weapon.
    • The lab detected traces of ricin in the package sent to the government building.