lassitude

n. [ L. lassitudo, fr. lassus faint, weary; akin to E. late: cf. F. lassitude. See Late. ] A condition of the body, or mind, when its voluntary functions are performed with difficulty, and only by a strong exertion of the will; languor; debility; weariness. [ 1913 Webster ]

The corporeal instruments of action being strained to a high pitch . . . will soon feel a lassitude. Barrow. [ 1913 Webster ]