overlay

Etymology 1

From Middle English overleyen, from Old English oferleċġan, from Proto-West Germanic *obarlaggjan, from Proto-Germanic *uberlagjaną, equivalent to over- + lay. Cognate with Saterland Frisian uurläze, úurlääse, Dutch overleggen, German Low German overleggen, överleggen, German überlegen, Swedish överlägga, Norwegian overlegge. Compare overlie.

verb

1. (transitive) To lay, spread, or apply something over or across; cover.
   The hillside at this point is composed of shaly rock overlaid with a peaty loam which carries a growth of heather, and its unstable condition has resulted in two landslides in the course of the railway's history. 1943 March and April, “A British Avalanche Shelter”, in Railway Magazine, page 80
2. To overwhelm; to press excessively upon.
3. (transitive, now rare, archaic) To lie over (someone, especially a child) in order to smother it; to suffocate.
   a heap of ashes that o'erlays your fire 1692, John Dryden, Cleomenes, the Spartan Hero, a Tragedy
   Prostitutes, thieves, girls who ‘overlaid’ their babies, abortionists who stuck their knitting needles into something vital – did they really need to be here? 1993, Pat Barker, The Eye in the Door (The Regeneration Trilogy), Penguin, published 2014, page 371
4. (transitive, printing) To put an overlay on.
5. (transitive, gambling) To bet too much money on.
   […] he has 'overlaid' his book, and has not succeeded in 'getting round' by bets against the other horses. 1890, The Twentieth Century, volume 27, page 934

noun

1. (printing) A piece of paper pasted upon the tympan sheet to improve the impression by making it stronger at a particular place.
2. (gambling) Odds which are set higher than expected or warranted. Favorable odds.
3. (horse racing) A horse going off at higher odds than it appears to warrant, based on its past performances.
4. A decal attached to a computer keyboard to relabel the keys.
   The keyboard overlay can be a memory jogger and a great help with spelling. In this way the keyboard makes word processing more accessible to younger as well as special needs children. 1994, Roger Frost, The IT in Secondary Science Book, page 56
5. (programming) A block of program code that is loaded over something previously loaded, so as to replace the functionality.
   This concept can be extended further by allowing a primary overlay to call a secondary overlay, and so on. However, we will limit ourselves here to the use of primary overlays. Before proceeding further, you need to understand the memory map of the computer, which is a diagram showing the use to which the memory of the computer is put. 1986, Noel M. Morris, Computer Graphics and CAD Fundamentals: BBC Micro Version
6. (Internet) A pop-up covering an existing part of the display.
7. (Scotland) A cravat.
8. A covering over something else.
   The first, on January 1, 1883, was attributed to the overlay becoming surcharged with water, due to insufficient drainage, and causing a slip. 1943 March and April, “A British Avalanche Shelter”, in Railway Magazine, page 80

Etymology 2

verb

1. simple past of overlie