Source : Webster's Revised Unabridged Dictionary (1913)

Layer \Lay"er\, n. [See {Lay} to cause to lie flat.]
   1. One who, or that which, lays.

   2. [Prob. a corruption of lair.] That which is laid; a
      stratum; a bed; one thickness, course, or fold laid over
      another; as, a layer of clay or of sand in the earth; a
      layer of bricks, or of plaster; the layers of an onion.

   3. A shoot or twig of a plant, not detached from the stock,
      laid under ground for growth or propagation.

   4. An artificial oyster bed.

Source : WordNet®

layer
     n 1: single thickness of usually some homogeneous substance;
          "slices of hard-boiled egg on a bed of spinach" [syn: {bed}]
     2: a relatively thin sheetlike expanse or region lying over or
        under another
     3: an abstract place usually conceived as having depth; "a good
        actor communicates on several levels"; "a simile has at
        least two layers of meaning"; "the mind functions on many
        strata simultaneously" [syn: {level}, {stratum}]
     4: a hen that lays eggs
     5: thin structure composed of a single thickness of cells
     v : make or form a layer; "layer the different colored sands"

Source : Free On-Line Dictionary of Computing

layer
     
        {protocol layer}