The Collaborative International Dictionary of English v.0.48:

Nestle \Nes"tle\, v. i. [imp. & p. p. Nestled; p. pr. & vb. n.
   Nestling.] [AS. nestlian.]
   1. To make and occupy a nest; to nest. [Obs.]
      [1913 Webster]

            The kingfisher . . . nestles in hollow banks.
                                                  --L'Estrange.
      [1913 Webster]

   2. To lie close and snug, as a bird in her nest; to cuddle
      up; to settle, as in a nest; to harbor; to take shelter.
      [1913 Webster]

            Their purpose was to fortify in some strong place of
            the wild country, and there nestle till succors
            came.                                 --Bacon.
      [1913 Webster]

            The children were nestled all snug in their beds
            While visions of sugarplums danced in their heads.
                                                  --Clement
                                                  Clarke Moore
                                                  (A Visit From
                                                  St. Nicholas,
                                                  (a poem
                                                  [1823]) also
                                                  called The
                                                  Night Before
                                                  Christmas).
      [PJC]

   3. To move about in one's place, like a bird when shaping the
      interior of her nest or a young bird getting close to the
      parent; as, a child nestles.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Nestling \Nes"tling\, a.
   Newly hatched; being yet in the nest.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Nestling \Nes"tling\ n.
   1. A young bird which has not abandoned the nest. --Piers
      Plowman.
      [1913 Webster]

   2. A nest; a receptacle. [Obs.] --Bacon.
      [1913 Webster]

WordNet (r) 3.0 (2006):

nestling
    n 1: young bird not yet fledged [syn: nestling, baby bird]
    2: a young person of either sex; "she writes books for
       children"; "they're just kids"; "`tiddler' is a British term
       for youngster" [syn: child, kid, youngster, minor,
       shaver, nipper, small fry, tiddler, tike, tyke,
       fry, nestling]

Moby Thesaurus II by Grady Ward, 1.0:

151 Moby Thesaurus words for "nestling":
   amorous dalliance, apprentice, avifauna, baby, baby bird, beginner,
   billing and cooing, bird, bird of Jove, bird of Juno,
   bird of Minerva, bird of night, bird of passage, bird of prey,
   birdie, birdlife, birdling, birdy, bundling, cage bird, calf,
   callow, caressing, catechumen, catling, chick, chickling, chicky,
   colt, cub, cuddling, cygnet, dalliance, deb, debutant, dewy,
   diving bird, dogie, dove, duckling, eagle, eaglet, entrant,
   ever-new, evergreen, fawn, firsthand, fish-eating bird, fledgling,
   flightless bird, foal, fondling, fowl, fresh, freshman,
   fruit-eating bird, fryer, fulmar, game bird, gosling, green,
   greenhorn, greeny, hugging, immature, infant, insect-eating bird,
   intact, kid, kissing, kit, kitten, lamb, lambkin, learner, litter,
   lollygagging, lovemaking, maiden, maidenly, migrant,
   migratory bird, necking, neophyte, neoteric, nest, new, newcomer,
   novice, novitiate, nuzzling, original, oscine bird, owl,
   passerine bird, peacock, peafowl, peahen, perching bird, petting,
   pigeon, piglet, pigling, polliwog, pristine, probationer, pullet,
   pup, puppy, ratite, raw, raw recruit, recruit, rookie, sea bird,
   seed-eating bird, sempervirent, sexual intercourse, shoat,
   shore bird, snuggling, songbird, spooning, squab, storm petrel,
   stormy petrel, swan, tadpole, tenderfoot, trainee, tyro, unbeaten,
   undeveloped, unfledged, unhandled, untouched, untried, untrodden,
   unused, vernal, virgin, virginal, wading bird, warbler, water bird,
   waterfowl, weaner, whelp, wildfowl, yeanling, young