A parchment MS on which a text has been written over a previous writing which can sometimes be recovered by ultraviolet photography.
Citation for palimpsest
Citation styles are based on the Chicago Manual of Style, 15th Ed., and the MLA Style Manual, 2nd Ed..
MLA
"palimpsest." In A Dictionary of the Bible. Ed. W. R. F. Browning. Oxford Biblical Studies Online. May 24, 2013. <http://www.oxfordbiblicalcstudies.com/article/opr/t94/e1400>.
Chicago
"palimpsest." In A Dictionary of the Bible. , edited by W. R. F. Browning. Oxford Biblical Studies Online, http://www.oxfordbiblicalcstudies.com/article/opr/t94/e1400 (accessed May 24, 2013).