Source : Webster's Revised Unabridged Dictionary (1913)

Everlastingly \Ev`er*last"ing*ly\, adv.
   In an everlasting manner.

Source : WordNet®

everlastingly
     adv : for a limitless time; "no one can live forever"; "brightly
           beams our Father's mercy from his lighthouse evermore"-
           P.P.Bliss [syn: {eternally}, {forever}, {evermore}]