poisonous             
adjective uk/ˈpɔɪ.zən.əs/ us/ˈpɔɪ.zən.əs/
B2 有毒的,有害的
very harmful and able to cause illness or death
  poisonous chemicals 有毒化学物质 
 Can you tell the difference between poisonous mushrooms and edible varieties? 你能说出有毒蘑菇和食用蘑菇之间的区别吗? 
 Synonym: toxic (POISONOUS)
 B2 (动物或昆虫)有毒的
A poisonous animal or insect uses poison in order to defend itself.
  a poisonous snake 毒蛇 
 Synonym: venomous (POISON)
  令人不快的;恶意的
very unpleasant and unkind
  He said some poisonous things to me. 他对我说了些恶毒的话。 
 - More examples
 - Carbon monoxide is a colourless, odourless, poisonous gas.
 - These normally harmless substances combine to form a highly poisonous gas.
 - Thousands of fish were killed as a result of a discharge of poisonous chemicals from a nearby factory.
 - Fungus can be poisonous.
 - The chemicals can be poisonous if ingested.