WordNet (r) 3.0 (2006):

crybaby
    n 1: a person who lacks confidence, is irresolute and wishy-
         washy [syn: wimp, chicken, crybaby]
    2: a person given to excessive complaints and crying and whining
       [syn: whiner, complainer, moaner, sniveller,
       crybaby, bellyacher, grumbler, squawker]

Moby Thesaurus II by Grady Ward, 1.0:

26 Moby Thesaurus words for "crybaby":
   Milquetoast, baby, big baby, chicken, doormat, dull tool,
   gutless wonder, invertebrate, jellyfish, lightweight, meek soul,
   milksop, mollycoddle, namby-pamby, nebbish, nonentity, pansy,
   pantywaist, pushover, sad sack, sissy, softling, softy, sop,
   weak sister, weakling