influenceyoudaoicibaDictYouDict[influence 词源字典]
influence: [14] Influence began life as an astrological term. It was coined in medieval Latin as influentia from the present participle of Latin influere ‘flow in’, a compound verb based on fluere ‘flow’, and to begin with denoted a sort of fluid that was supposed to be given off by the stars and to influence human life. English originally acquired the word with this meaning, and it was not until the end of the 16th century that the main current sense ‘power to produce effects’ started to establish itself.

The more concrete notion of an ‘emanation’ that affected people also lay behind the use of Italian influenza for ‘epidemic’, from which English got influenza (see FLU). Another English acquisition from Latin influere is influx [17], which comes from its past participle.
=> flu, fluent, influx[influence etymology, influence origin, 英语词源]
influence (n.)youdaoicibaDictYouDict
late 14c., an astrological term, "streaming ethereal power from the stars acting upon character or destiny of men," from Old French influence "emanation from the stars that acts upon one's character and destiny" (13c.), also "a flow of water," from Medieval Latin influentia "a flowing in" (also used in the astrological sense), from Latin influentem (nominative influens), present participle of influere "to flow into," from in- "into, in, on, upon" (see in- (2)) + fluere "to flow" (see fluent). Meaning "exercise of personal power by human beings" is from mid-15c.; meaning "exertion of unseen influence by persons" is from 1580s (a sense already in Medieval Latin, for instance Aquinas). Under the influence "drunk" first attested 1866.
influence (v.)youdaoicibaDictYouDict
1650s, from influence (n.). Related: Influenced; influencing.