(ˈleɪ ər) n. one. a thickness of some content laid on or unfold over a surface area: a layer of soot to the window sill; two layers of paint. 2. mattress; stratum: alternating layers of basalt and sandstone. three. a person or point that lays: a carpet layer. 4. a hen held for egg output. five. one of a number of objects of garments worn one on