unutterable

Adjective

• very difficult to pronounce correctly
  • an unpronounceable foreign word
    
  • unutterable consonant clusters
    

• defying expression or description
  • indefinable yearnings
    
  • indescribable beauty
    
  • ineffable ecstasy
    
  • inexpressible anguish
    
  • unspeakable happiness
    
  • unutterable contempt
    
  • a thing of untellable splendor
    

• too sacred to be uttered
  • the ineffable name of the Deity
    

Related words

• Synonyms: 
  unpronounceable , indefinable , indescribable , ineffable , unspeakable , untellable , unnameable