WordNet (r) 3.0 (2006):

piglet
    n 1: a young pig [syn: piglet, piggy, shoat, shote]

Moby Thesaurus II by Grady Ward, 1.0:

46 Moby Thesaurus words for "piglet":
   barrow, birdling, boar, calf, catling, chick, chickling, chicky,
   colt, cub, dogie, duckling, fawn, fledgling, foal, fryer, gilt,
   gosling, hog, kid, kit, kitten, lamb, lambkin, litter, nest,
   nestling, pig, piggy, pigling, polliwog, porker, pullet, pup,
   puppy, razorback, shoat, sow, suckling pig, swine, tadpole, tusker,
   weaner, whelp, wild boar, yeanling