1. too bad, shocking, or terrible to describe in words
2. not able or allowed to be spoken or mentioned

Examples

• The conditions in the prison were unspeakable.
• She witnessed unspeakable horrors during the war.
• The tragedy brought unspeakable grief to the family.
• His name became unspeakable after the scandal.
• There was an unspeakable sadness in her eyes.
• The crime was so unspeakable that reporters struggled to describe it.
• In some cultures, certain topics remain unspeakable in public.