lay·er / ˈlāər/ • n. 1. a sheet, quantity, or thickness of material, typically one of several, covering a surface or body: bears depend on a layer of blubber to keep them warm in the water fig. a larger missile would provide a layer of defense at higher altitudes. ∎  a level of seniority in the hierarchy of an organization: a managerial layer.2. [in combination] a person or thing that lays something: the worms are prolific egg-layers. ∎  a hen that lays eggs.3. a shoot fastened down to take root while attached to the parent plant.• v. [tr.] [often as adj.] (layered) 1. arrange in a layer or layers: the current trend for layered clothes. ∎  cut (hair) in overlapping layers: her layered, shoulder-length hair.2. propagate (a plant) as a layer: a layered shoot.

layer
A. one who lays XIV;

B. thickness of matter spread over a surface;

C. shoot or twig pegged down to take root XVII. Several words appeared to have coalesced under one form, all ostensibly f. LAY1 + -ER1; in sense B the earliest form is lear, which may be a var. of LAIR; sense C may be after synon. Du. (af)legger.

layer in open systems interconnection (OSI). See seven-layer reference model.

Layer

a substance or things grouped together and lying between two other horizontal strata. See also pocket.