Is it farther or further?
Old English *-flycge (Kentish -flecge),an adjective meaning "having the feathers, fit to fly," from West Germanic *fluggja- (cf. Middle Dutch vlugge, Low German flügge), from root meaning "to fly" (see fly (v.)). As a verb, it is first attested in English 1560s. Related: Fledged; fledging.