indescribable
1. [ adjective ] defying expression or description
Synonyms: unspeakable ineffable untellable unutterable indefinable
Examples:

"indefinable yearnings" "indescribable beauty" "ineffable ecstasy" "inexpressible anguish" "unspeakable happiness" "unutterable contempt" "a thing of untellable splendor"

Related terms: inexpressible
Similar spelling:   indescribably
  indiscernible
  indiscriminate
  indiscriminately