Source : Webster's Revised Unabridged Dictionary (1913)

Palimpsest \Pal"imp*sest\, n. [L. palimpsestus, Gr. ? scratched
   or scraped again, ? a palimpsest; ? again + ? to rub, rub
   away: cf. F. palimpseste.]
   A parchment which has been written upon twice, the first
   writing having been erased to make place for the second.
   --Longfellow.

Source : WordNet®

palimpsest
     n : a manuscript (usually written on papyrus or parchment) on
         which more than one text has been written with the
         earlier writing incompletely erased and still visible