The Free On-line Dictionary of Computing (30 December 2018):

Open Systems Interconnection
ISO seven layer model
Open Systems Interconnect
OSI Model
OSI Reference Model
OSI-RM
OSI seven layer model
seven layer model

    (OSI-RM, OSI Reference Model, seven layer model)
   A model of network architecture and a suite of protocols (a
   protocol stack) to implement it, developed by ISO in 1978
   as a framework for international standards in heterogeneous
   computer network architecture.

   The OSI architecture is split between seven layers, from
   lowest to highest: 1 physical layer, 2 data link layer, 3
   network layer, 4 transport layer, 5 session layer, 6
   presentation layer, 7 application layer.

   Each layer uses the layer immediately below it and provides a
   service to the layer above.  In some implementations a layer
   may itself be composed of sub-layers.

   OSI is the umbrella name for a series of non-proprietary
   protocols and specifications, comprising, among others, the
   OSI Reference Model, ASN.1 (Abstract Syntax Notation 1), BER
   (Basic Encoding Rules), CMIP and CMIS (Common Management
   Information Protocol and Services), X.400 (Message Handling
   System, or MHS), X.500 (Directory Service), Z39.50 (search
   and retrieval protocol used by WAIS), and many others.
   Apart from its actual application to real protocols, it also
   serves as a useful teaching model.

   (2004-02-13)