Adiabatic process
Also: Adiabatic
"An adiabatic process is a process in which no external heat is gained or lost by the system. The opposite is called a diabatic process."
In studying the Thermodynamics of a system or process it is important to know whether the behavior that is observed occurred in a situation where no heat was added or lost (Adiabatic) or whether there was heat gain or loss (Diabatic)
Definition based on (revised from) IPCC AR4.
All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.