Wiktionary
n. 1 (context physics English) The characteristic time for a system to reach an equilibrium condition after a disturbance 2 (context medicine English) The time taken for a muscle to revert to its resting state after being used
WordNet
n. the time constant of an exponential return of a system to equilibrium after a disturbance
Usage examples of "relaxation time".
Refusing to dissipate, it impaired her ability to cogently cogitate, robbed her of relaxation time, and had started to affect her even when she slept.
The War for Winterhome was finally under way, and his relaxation time was all too rare.
He works so hard to keep himself in check that it's beginning to have an adverse effect on him, and I would very much recommend some off-ship relaxation time for him, whether he objects or not.
Seven till eight is compulsory relaxation time in Action Centre, and all the zappy Actioneers were off busily relaxing in the most complex, stressful and career-orientated ways they could find.