perfidious

Adjective

• tending to betray; especially having a treacherous character as attributed to the Carthaginians by the Romans
  • Punic faith
    
  • the perfidious Judas
    
  • the fiercest and most treacherous of foes
    
  • treacherous intrigues
    

Related words

• Synonyms: 
  punic , treacherous