unforgiving

Adjective

• not to be placated or appeased or moved by entreaty
  • grim determination
    
  • grim necessity
    
  • Russia's final hour, it seemed, approached with inexorable certainty
    
  • relentless persecution
    
  • the stern demands of parenthood
    

• unwilling or unable to forgive or show mercy
  • a surly unforgiving old woman
    

Related words

• Synonyms: 
  grim , inexorable , relentless , stern , unappeasable , unrelenting