Webster's Revised Unabridged Dictionary · 1913

Unspeakable

Unspeakable , adjective

[Prefix un- not + speakable.]

Not speakable; incapable of being uttered or adequately described; inexpressible; unutterable; ineffable; as, unspeakable grief or rage.
Ye rejoice with joy unspeakable and full of glory. — 1 Pet. i. 8