Wikipedia
CVAR
CVAR and ConVar are abbreviations for Console Variable. Depending on the context in which the term is found, it may also stand for Client Variable, or Configuration Variable.
This is a type of variable used in many computer games and computer 3D simulation engines that can be manipulated by a text based command line interface within the game or engine, often called a console. They commonly hold configuration parameters, but can be used for anything that may potentially be accessed and/or modified by the console.
The most common usage of CVARs is by server operators to customize their online game servers.