Origin and history of layer

"to cause to lie or rest," Middle English leien, from Old English lecgan "to place on the ground (or other surface); place in an orderly fashion," also "put down" (often by striking), from Proto-Germanic *lagojanan. This is reconstructed to be from PIE root *legh- "to lie down, lay." This is the causative form of the ancient Germanic verb that became modern English lie (v.2).

The meaning "have sex with" is recorded by 1934, in U.S. slang, probably from sense of "bring forth and deposit" (which was in Old English, as in lay an egg, lay a bet, etc.), perhaps reinforced by to lie with, a phrase frequently met in the Bible. To lay for (someone) "await a chance at revenge" is from late 15c. To lay low "stay inconspicuous" is from 1839; to lay (someone) low "defeat, humble, kill" (late 14c.) preserves the secondary Old English sense. To lay aside (transitive) is by late 14c., "to put to one side or out of the way for a time or for a purpose," also from Middle English as "put away permanently, give up."

Germanic cognates include Old Saxon leggian, Old Norse leggja, Old Frisian ledza, Middle Dutch legghan, Dutch leggen, Old High German lecken, German legen, Gothic lagjan "to lay, put, place."

also brick-layer, "one who builds with bricks," late 15c., from brick (n.) + layer in the original sense. Related: Bricklaying.