Definition of adiabatic:
(adj) :
(physics, thermodynamics, of a process) Without gain or loss of heat (and thus with no change in entropy, in the quasistatic approximation).
(adj) :
(physics, quantum mechanics, of a process) Involving the slow change of the Hamiltonian of a system from its initial value to a final value.
(n) :
An adiabatic curve or graph