The Collaborative International Dictionary of English v.0.48:

Duckling \Duck"ling\, n.
   A young or little duck. --Gay. Duckmeat

WordNet (r) 3.0 (2006):

duckling
    n 1: flesh of a young domestic duck
    2: young duck

Moby Thesaurus II by Grady Ward, 1.0:

120 Moby Thesaurus words for "duckling":
   Bantam, Cornish hen, angel, babe, baby, baby-doll, banty,
   barn-door fowl, barnyard fowl, biddy, birdling, broiler, brooder,
   broody hen, buttercup, caille, calf, canard, caneton, capon,
   catling, chanticleer, chapon, cherub, chick, chickabiddy, chicken,
   chickling, chicky, cock, cockerel, colt, cub, darling, dear, deary,
   dindon, dogie, doll, domestic fowl, drake, duck, dunghill fowl,
   faisan, fawn, fledgling, foal, fowl, fryer, game fowl, gander,
   gobbler, goose, gosling, grouse, guinea cock, guinea fowl,
   guinea hen, hen, hen turkey, hon, honey, honey bunch, honey child,
   kid, kit, kitten, lamb, lambkin, litter, love, lover, nest,
   nestling, oie, partlet, partridge, pet, petkins, pheasant, pigeon,
   pigeonneau, piglet, pigling, polliwog, poulard, poulet, poult,
   poultry, precious, precious heart, pullet, pup, puppy, quail,
   roaster, rooster, setting hen, shoat, snookums, spring chicken,
   squab, stewing chicken, sugar, sweet, sweetheart, sweetie,
   sweetkins, sweets, tadpole, tom, tom turkey, turkey,
   turkey gobbler, turkey-cock, volaille, weaner, whelp, wild duck,
   yeanling