† delaˈssationObs.rare—1. [n. of action f. L. dēlassāre to weary or tire out, f.de-, de- I. 3 + lassāre to weary.] Fatigue, weariness. 1692Ray Dissol. World ii. ii. (1732) 102 [The birds] are able to continue longer on the Wing without Delassation.1727Bailey vol. II, Delassation, a tiring or wearying.