1. (Originally from Multics, widely propagated via Unix) The command interpreter used to pass commands to an operating system so called because it is the part of the operating system that interfaces with the outside world. The commonest Unix shells are the c shell (csh) and the Bourne shell (sh). 2. (Or "wrapper") Any interface program that mediates access to a special resource or server for convenience, efficiency, or security reasons for this meaning, the usage is usually "a shell around" whatever. [Jargon File] (1995-05-11)
