Source : Webster's Revised Unabridged Dictionary (1913)

Unspeakable \Un*speak"a*ble\, a. [Pref. un- not + speakable.]
   Not speakable; incapable of being uttered or adequately
   described; inexpressible; unutterable; ineffable; as,
   unspeakable grief or rage. -- {Un*speak"a*bly}, adv.

         Ye rejoice with joy unspeakable and full of glory. --1
                                                  Pet. i. 8.

Source : WordNet®

unspeakably
     adv : to an inexpressible degree; "she was looking very young
           tonight, and, as usual, indescribably beautiful, in a
           simple strapless dress of a green and white silky
           cotton" [syn: {ineffably}, {indescribably}, {unutterably}]