a layer or decoration of something applied: an overlay of gold.
7.
Printing.
a.
a shaped piece of paper, or a sheet of paper reinforced at the proper places by shaped pieces, put on the tympan of a press to increase or equalize the impression.
b.
a method of preparing copy for multicolor printing, in which matter for each color is prepared on a transparent sheet that is placed over a key plate, usually the one to be printed in black.
c.
the sheet or sheets so prepared.
8.
a sheet of transparent paper placed over a photograph, a dummy, or other artwork for noting corrections, instructions, mechanical separations, etc.
9.
Computers. software or data in external storage and brought into main storage for execution by replacing or augmenting software or data already there.