adiabatic (adj.) Look up adiabatic at Dictionary.com
"without transference, impossible (to heat)," 1838, with -ic + Greek adiabatos "not to be passed" (of rivers, etc.), from a- "not" (see a- (3)) + diabatos "to be crossed or passed, fordable," from dia "through" (see dia-) + batos "passable," from bainein "to go, walk, step," from PIE root *gwā- "to go, to come" (see come). In thermodynamics, of a change in volume without change in heat.