The Collaborative International Dictionary of English v.0.48:
Overlay \O`ver*lay"\, v. t. [imp. & p. p. Overlaid; p. pr. &
vb. n. Overlaying.]
1. To lay, or spread, something over or across; hence, to
cover; to overwhelm; to press excessively upon.
When any country is overlaid by the multitude which
live upon it. --Sir W.
As when a cloud his beams doth overlay. --Spenser.
Framed of cedar overlaid with gold. --Milton.
With this portentous bridge the dark abyss.
2. Specifically: To cover (an object made of an inexpensive
metal, glass, or other material) with a thin sheet of an
expensive metal, especially with silver or gold.
Distinguished from to plate, which is done by a chemical
or electrical deposition process.
3. To smother with a close covering, or by lying upon.
This woman's child died in the night; because she
overlaid it. --1 Kings iii.
A heap of ashes that o'erlays your fire. --Dryden.
4. (Printing) To put an overlay on.