fledgeyoudaoicibaDictYouDict[fledge 词源字典]
fledge: [16] The notion underlying fledge is the ‘ability to fly’. Historically, the idea of ‘having feathers’ is simply a secondary development of that underlying notion. The verb comes from an obsolete adjective fledge ‘feathered’, which goes back ultimately to a pre-historic West Germanic *fluggja (source also of German flügge ‘fledged’). This was derived from a variant of the base which produced English fly.

There is no immediate connection with fletcher ‘arrowmaker’ [14], despite the formal resemblance and the semantic connection with ‘putting feathered flights on arrows’, but further back in time there may be a link. Fletcher came from Old French flechier, a derivative of fleche ‘arrow’. A possible source for this was an unrecorded Frankish *fliugika, which, like fledge, could be traceable back to the same Germanic ancestor as that of English fly.
=> fly[fledge etymology, fledge origin, 英语词源]
fledge (v.)youdaoicibaDictYouDict
"to acquire feathers," 1560s, from Old English adjective *-flycge (Kentish -flecge; in unfligge "featherless," glossing Latin implumes) "having the feathers developed, fit to fly," from Proto-Germanic *flugja- "ready to fly" (cognates: Middle Dutch vlugge, Low German flügge), from PIE *pleuk- "to fly" (see fletcher). Meaning "bring up a bird" (until it can fly on its own) is from 1580s. Related: Fledged; fledging.