The Collaborative International Dictionary of English v.0.48:

Cygnet \Cyg"net\ (s[i^]g"n[e^]t), n. [Dim. of F. cygne swan, L.
   cycnus. cygnus, fr. Gr. ky`klos: but F. cygne seems to be an
   etymological spelling of OF. cisne, fr. LL. cecinus, cicinus,
   perh. ultimately also fr. Gr. ky`klos.] (Zool.)
   A young swan. --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cygnet
    n 1: a young swan

Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "cygnet":
   avifauna, baby bird, bird, bird of Jove, bird of Juno,
   bird of Minerva, bird of night, bird of passage, bird of prey,
   birdie, birdlife, birdy, cage bird, chick, diving bird, dove,
   eagle, eaglet, fish-eating bird, fledgling, flightless bird, fowl,
   fruit-eating bird, fulmar, game bird, insect-eating bird, migrant,
   migratory bird, nestling, oscine bird, owl, passerine bird,
   peacock, peafowl, peahen, perching bird, pigeon, ratite, sea bird,
   seed-eating bird, shore bird, songbird, squab, storm petrel,
   stormy petrel, swan, wading bird, warbler, water bird, waterfowl,
   wildfowl



U.S. Gazetteer Places (2000):

Cygnet, OH -- U.S. village in Ohio
   Population (2000):    564
   Housing Units (2000): 222
   Land area (2000):     0.337310 sq. miles (0.873630 sq. km)
   Water area (2000):    0.001409 sq. miles (0.003649 sq. km)
   Total area (2000):    0.338719 sq. miles (0.877279 sq. km)
   FIPS code:            19820
   Located within:       Ohio (OH), FIPS 39
   Location:             41.241093 N, 83.643500 W
   ZIP Codes (1990):     43413
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Cygnet, OH
    Cygnet