late 14c., "rupture; mid-15c., "remission of a burden or penalty," from Old French relaxacion (14c.) and directly from Latin relaxationem (nominative relaxatio) "an easing, mitigation, relaxation," noun of action from past participle stem of relaxare (see relax). Meaning "relief from hard work or ordinary cares" is from 1540s.
relaxation re·lax·a·tion (rē'lāk-sā'shən)
n.
The act of relaxing or the state of being relaxed.
Refreshment of body or mind.
A loosening or slackening.
The lengthening of inactive muscle or muscle fibers.