ineffably

from WordNet (r) 3.0 (2006)

ineffably
    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

Ineffably \In*ef"fa*bly\, adv.
   In a manner not to be expressed in words; unspeakably.
   --Milton.
   [1913 Webster]