The Collaborative International Dictionary of English v.0.48:

fledgeling \fledgeling\, fledgling \fledgling\n.
   a new member of a group.

   Syn: newcomer, fledgeling, starter, neophyte, freshman,
        entrant.
        [WordNet 1.5]

   2. A young bird just fledged. [WordNet sense 2]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

fledgling \fledgling\ adj.
   1. having just acquired its flight feathers; -- of a young
      bird; as, a fledgling robin. [prenominal]

   Syn: fledgeling(prenominal).
        [WordNet 1.5]

   2. young and inexperienced; as, a fledgling enterprise; a
      fledgling skier.

   Syn: unfledged.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

fledgling
    adj 1: (of a young bird) having acquired its flight feathers; "a
           fledgling robin" [syn: fledgling(a), fledgeling(a)]
    2: young and inexperienced; "a fledgling enterprise"; "a
       fledgling skier"; "an unfledged lawyer" [syn: fledgling,
       unfledged, callow]
    n 1: any new participant in some activity [syn: newcomer,
         fledgling, fledgeling, starter, neophyte,
         freshman, newbie, entrant]
    2: young bird that has just fledged or become capable of flying
       [syn: fledgling, fledgeling]

Moby Thesaurus II by Grady Ward, 1.0:

213 Moby Thesaurus words for "fledgling":
   Young Turk, abecedarian, adolescent, alphabetarian, apprentice,
   arriviste, articled clerk, at half cock, avifauna, baby, baby bird,
   beginner, bird, bird of Jove, bird of Juno, bird of Minerva,
   bird of night, bird of passage, bird of prey, birdie, birdlife,
   birdling, birdy, boot, boy, bright young man, bub, bubba, buck,
   bud, buddy, cage bird, calf, callow, catechumen, catling, chick,
   chickling, chicky, colt, comer, cub, cygnet, deb, debutant, dewy,
   diving bird, dogie, dove, duckling, eagle, eaglet, entrant,
   ever-new, evergreen, fawn, fellow, firsthand, fish-eating bird,
   flightless bird, foal, fowl, fresh, freshman, fruit-eating bird,
   fryer, fulmar, game bird, gosling, green, greenhorn, greeny,
   half-baked, half-cocked, half-grown, hobbledehoy, hopeful,
   ignoramus, ill-digested, immature, impubic, inductee, infant,
   initiate, insect-eating bird, intact, junior, juvenal, juvenile,
   kid, kit, kitten, lad, laddie, lamb, lambkin, learner, litter,
   maiden, maidenly, manchild, master, migrant, migratory bird, minor,
   modern, modern generation, modern man, modernist, modernizer,
   muchacho, neologism, neologist, neology, neonate, neophyte,
   neoteric, neoterism, neoterist, nest, nestling, new, new boy,
   new generation, new man, newcomer, nouveau riche, novice,
   novitiate, novus homo, original, oscine bird, owl, parvenu,
   passerine bird, peacock, peafowl, peahen, perching bird, pigeon,
   piglet, pigling, polliwog, postulant, pristine, probationer,
   probationist, pubescent, pullet, pup, puppy, ratite, raw,
   raw recruit, recruit, rising generation, rookie, sapling,
   schoolboy, sea bird, seed-eating bird, sempervirent, shoat,
   shore bird, slip, songbird, sonny, sonny boy, sprig, squab,
   storm petrel, stormy petrel, stripling, swan, tadpole, teenager,
   teener, teenybopper, tenderfoot, trainee, tyro, unbeaten,
   underripe, undeveloped, unfledged, unmellowed, unripe, unseasoned,
   untouched, untried, untrodden, unused, upstart, vernal, virgin,
   virginal, wading bird, warbler, water bird, waterfowl, weaner,
   whelp, wildfowl, yeanling, young, young hopeful, young man,
   young person, younger, youngest, youngling, youngster, youth