unsayable
/ʌnˈseɪəbəl/Definitions
1. adjective
Too unpleasant or indelicate to be expressed in words.
“The tragedy of the event was almost unsayable, leaving everyone stunned.”
2. noun
A thing that is too unpleasant or difficult to be expressed or put into words.
“The unsayable truth about her past was finally revealed to her family.”