fleeyoudaoicibaDictYouDict[flee 词源字典]
flee: [OE] Flee, like its close relatives German fliehe, Dutch vlieden, and Swedish and Danish fly, comes from a prehistoric Germanic *thleukhan, a word of unknown origin. In Old English, flee and fly had the same past tense and past participle (and indeed the same derivatives, represented in modern English by flight), and this, together with a certain similarity in meaning, has led to the two verbs being associated and often confused, but there is no reliable evidence that they are etymologically connected.
[flee etymology, flee origin, 英语词源]
flee (v.)youdaoicibaDictYouDict
Old English fleon, flion "take flight, fly from, avoid, escape" (contracted class II strong verb; past tense fleah, past participle flogen), from Proto-Germanic *fleuhan "to run away" (cognates: Old High German fliohan, Old Norse flöja, Old Frisian flia, Dutch vlieden, German fliehen, Gothic þliuhan "to flee"), probably from PIE *pleuk-, extended form of root *pleu- "to flow" (see pluvial). Also compare fly (v.2).

Weak past tense and past participle fled emerged in Middle English under influence of Scandinavian. Old English had a transitive form, geflieman "put to flight, banish, drive away," which came in handy in the Anglo-Saxon Chronicle. Related: fled; Fleeing.