"Originally: severe physical weakness; prostration; debility", Mid 18th cent.; earliest use found in Robert James (d. 1776), physician and inventor of James's fever powder. From post-classical Latin adynamia from ancient Greek ἀδυναμία lack of strength, weakness, debility from ἀ + δύναμις power + -ία.[adynamia etymology, adynamia origin, 英语词源]