Process in which no heat enters or leaves a Definable part of the universe that can be open, closed, or isolated. An open system exchanges both matter and energy with its surroundings. A closed system can only exchange energy with its surroundings; it has walls through which heat can pass. An isolated system cannot exchange energy or matter with. This is the case, for example, when an interstellar gas cloud expands or contracts. Adiabatic changes are usually accompanied by changes in temperature or volume.
Some or all content above used with permission from J. H. Wittke.