adiabatic

1. (physics, thermodynamics, of a process) Without gain or loss of heat (and thus with no change in entropy, in the quasistatic approximation).Examples: "The line drawn on the indicator diagram in the latter case has been named by Professor Rankine an Adiabatic line, because it is defined by the condition that heat is not allowed to pass through (διαβαίνειν) the vessel which confines the substance."; "Talk of dynamic compression and adiabatic gradients didn't carry as much weight as the certainty of its conscious intent."Antonyms: diabaticnot-comparable

2. (physics, quantum mechanics, of a process) Involving the slow change of the Hamiltonian of a system from its initial value to a final value.Examples: "In this section we examine the limiting cases when T is very small (sudden change) and very large (adiabatic change)."Antonyms: nonadiabaticnot-comparable