This glossary defines terms in the field of Modeling and Simulation. Topics covered include general modeling and simulation concepts, types of models and simulations, modeling and simulation variables, game theory, and queueing theory. Terms were excluded if they were considered to be parochial to one group or organization; company proprietary or trademarked; multi-word terms whose meaning could be inferred from the definitions of the component words; or terms whose meaning in the computer field could be directly inferred from their standard English meaning. Some technical terms that appear in the definitions are defined in other P610 glossaries and are not included as entries here.