(Greek:  παλίμψηστος , “scraped again”).  A manuscript from which the original writing has been scraped or washed off so that the pages could be re-used for another document. Traces of the original writing remain, making it possible for scholars to discern and decipher it.  A number of ancient works have survived only as palimpsests.

The Archimedes Palimpsest. Ink on parchment. 10th and 13th centuries. Walters Art Museum, Baltimore.