(ˈleɪ ər) n. one. a thickness of some materials laid on or spread in excess of a floor: a layer of soot over the window sill; two layers of paint. 2. bed; stratum: alternating layers of basalt and sandstone. 3. anyone or matter that lays: a carpet layer. 4. a hen saved for egg generation. five. one among several merchandise of apparel worn one a