The Full Form of JIS is Joint Integrated Simulation.

The joint simulation system, or JSIMS, is a single, seamlessly integrated joint synthetic battlespace that provides a common environmental and operational picture of the battle area, an effective combat adjudication process, and a robust after-action review capability. Objects can be composed to create a simulation to support joint or service or agency training, mission rehearsal or educational objectives. Instructors will be able to tailor a simulation environment to meet requirements derived from mission analysis using the universal joint task list and appropriate service task lists under the conditions and to the standards set by the commander.