platen (n.)

1540s, "flat plate of metal," from Middle French plateine, from Old French platine "flat piece, metal plate" (13c.), perhaps altered (by influence of plat "flat") from patene, from Latin patina "pan; broad, shallow dish," from Greek patane "plate, dish" (from PIE root *pete- "to spread"). From 1590s as "the flat part of a press which comes down upon the form and by which the impression is made." Hence, on a typewriter, "cylindrical roller or other surface against which the paper is held" (1890).