indescribably

from WordNet (r) 3.0 (2006)

indescribably
    adv 1: 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},
           {unspeakably}]

from The Collaborative International Dictionary of English v.0.48

Indescribably \In`de*scrib"a*bly\, adv.
   In an indescribable manner; to a degree impossible to
   desribe; as, indescribably beautiful.
   [PJC]