High Quality Content by WIKIPEDIA articles! An adiabatic process is any process occurring without gain or loss of heat within a system (i.e. during the process the system is thermodynamically isolated- there is no heat transfer with the surroundings). This is the opposite of a diabatic process, where there is heat transfer. A key concept in thermodynamics, many rapid chemical and physical processes are described or approximated in this way. Such processes are usually followed or preceded by events that do involve heat transfer (i.e. are non-adiabatic). Examples include electron-transfer.