fledge
/fledʒ/verb
no obj.
1- (of a young bird) develop wing feathers that are large enough for flight（幼鸟）长出飞羽。
1.1
- with obj. bring up (a young bird) until its wing feathers are developed enough for flight把（幼鸟）养至长出飞羽。
词源
mid 16th cent.: from the obsolete adjective fledge 'ready to fly', from Old English, of Germanic origin; related to Dutch vlug 'quick, agile', also to FLY1.