WordNet (r) 3.0 (2006):

play down
    v 1: understate the importance or quality of; "he played down
         his royal ancestry" [syn: background, play down,
         downplay] [ant: foreground, highlight, play up,
         spotlight]

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "play down":
   abate, allay, alleviate, assuage, attemper, bank the fire, bedwarf,
   belittle, blunt, chasten, constrain, control, damp, dampen,
   de-emphasize, deaden, deprecate, depreciate, detract from,
   diminish, downplay, dull, dwarf, extenuate, keep within bounds,
   lay, lenify, lessen, lighten, make light of, make little of,
   make nothing of, minify, minimize, mitigate, moderate, modulate,
   mute, obtund, palliate, reduce, reduce the temperature, restrain,
   set at naught, set little by, slacken, slow down, smother, sober,
   sober down, soft-pedal, soften, stifle, subdue, suppress, tame,
   temper, think little of, think nothing of, tone down, tune down,
   underplay, weaken