poisonous
adjective /ˈpɔɪzənəs/
  /ˈpɔɪzənəs/
- causing death or illness if swallowed or taken into the body synonym toxic
- poisonous chemicals/fumes/plants
 - a poisonous substance
 - This gas is highly poisonous.
 - poisonous to somebody/something The leaves of certain trees are poisonous to cattle.
 
Oxford Collocations Dictionaryverbs- be
 - become
 
- deadly
 - extremely
 - highly
 - …
 
- to
 
 - (of animals and insects) producing a poison that can cause death or illness if the animal or insect bites you synonym venomous
- poisonous snakes
 - a tiny spider with a poisonous bite
 
Oxford Collocations Dictionaryverbs- be
 - become
 
- deadly
 - extremely
 - highly
 - …
 
- to
 
 - extremely unpleasant or unfriendly 
- a poisonous person
 - the poisonous atmosphere in the office