10 letters · 17 points in Scrabble
noun (physiology) the gradual lengthening of inactive muscle or muscle fibers
noun (physics) the exponential return of a system to equilibrium after a disturbance
noun a feeling of refreshing tranquility and an absence of tension or worry
originBorrowed from Latin relaxatio, relaxationis; equivalent to relax + -ation.
Etymology from Wiktionary, CC BY-SA 3.0