Overlay meaning : A piece of paper pasted upon the tympan sheet to improve the impression by making it stronger at a particular place. (betting) Odds which are set higher than expected or warranted. Favorable odds. A horse going off at higher odds than it appears to warrant, based on its past performances. A decal attached to a computer keyboard to relabel the keys. A block of program code that is loaded over something previously loaded, so as to replace the functionality. A pop-up covering an existing part of the display. A cravat. To lay, spread, or apply something over or across; cover. To overwhelm; to press excessively upon. To lie over (someone, especially a child) in order to smother it; to suffocate. To put an overlay on.