- that cannot be spoken
- marvelous, awesome, etc.; beyond human expression; ineffable
- so bad, evil, etc. as to defy description
- so foul, evil, etc. as to be unfit to be described or discussed: unspeakable depravity
- Beyond description; inexpressible: unspeakable happiness.
- Inexpressibly bad or objectionable: unspeakable poverty.
- Not to be spoken: unspeakable thoughts.