WordNet (r) 3.0 (2006):

pushover
    n 1: someone who is easily taken advantage of
    2: any undertaking that is easy to do; "marketing this product
       will be no picnic" [syn: cinch, breeze, picnic, snap,
       duck soup, child's play, pushover, walkover, piece
       of cake]

Moby Thesaurus II by Grady Ward, 1.0:

115 Moby Thesaurus words for "pushover":
   Cadmean victory, KO, Milquetoast, Pyrrhic victory, ascendancy,
   babe, baby, big baby, boob, breeze, championship, chicken, chump,
   cinch, cipher, conquest, credulous person, crybaby, cull, doormat,
   duck, dud, dull tool, dummy, dupe, easy mark, easy pickings,
   easy target, easy thing, easy victory, fall guy, fish, fool,
   gobe-mouches, grand slam, greener, greenhorn, greeny, gudgeon,
   gull, gutless wonder, hollow man, innocent, invertebrate,
   jackstraw, jellyfish, knockout, landslide, landslide victory,
   lay figure, lead-pipe cinch, leadpipe cinch, lightweight,
   man of straw, mastery, meek soul, milksop, mollycoddle, monkey,
   moral victory, mug, namby-pamby, nebbish, nobody, nonentity,
   nothing, nullity, pansy, pantywaist, patsy, picnic, pie,
   piece of cake, pigeon, pipe, plaything, prize sap, puppet,
   runaway victory, sad sack, sap, saphead, schlemiel, setup,
   sinecure, sissy, sitting duck, snap, soft touch, softling, softy,
   sop, stooge, subdual, subduing, success, sucker, sure thing,
   thing of naught, total victory, toy, trifle, triumph,
   trusting soul, velvet, victim, victory, walkaway, walkover,
   weak sister, weakling, win, winning, winning streak, zero