'Platen' definitions:

Definition of 'platen'

(from WordNet)
noun
Work table of a machine tool
noun
The flat plate of a printing press that presses the paper against the type
noun
The roller on a typewriter against which the keys strike

Definition of 'Platen'

From: GCIDE
  • Platen \Plat"en\, n. [F. platine, fr. plat flat. See Plate, and cf. Platin.] (Mach.) (a) The part of a printing press which presses the paper against the type and by which the impression is made. (b) Hence, an analogous part of a typewriter, on which the paper rests to receive an impression. (c) The movable table of a machine tool, as a planer, on which the work is fastened, and presented to the action of the tool; -- also called table. [1913 Webster]