business jargon The number units of a particular product or service that are currently in use, especially software or an Internet or computing platform. (Also referred to as "install(ed) user base" or simply "user base.") There have been fears that the computer giant's existing installed base may decline after their newest operating system is implemented.
See also: base
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.