1. A relatively thin sheetlike expanse or region lying over or under another SYN. level, stratum, sheet.
2. A single thickness of usually some homogeneous substance.
3. Thin structure composed of a single thickness of cells.

To make or form a layer

1. The protocol or protocols operating at a particular level within a protocol suite, such as IP within the TCP/IP suite. Each layer is responsible for providing specific services or functions for computers exchanging information over a communications network (such as the layers in the ISO/OSI reference model) and information is passed from one layer to the next. Although different suites have varying numbers of levels, generally the highest layer deals with software interactions at the application level, and the lowest governs hardware-level connections between different computers. See the table. See also ISO/OSI reference model, protocol stack, TCP/IP.
2. In communications and distributed processing, a set of rules and standards that handles a particular class of events.