WordNet (r) 3.0 (2006):

push down
    v 1: cause to come or go down; "The policeman downed the heavily
         armed suspect"; "The mugger knocked down the old lady after
         she refused to hand over her wallet" [syn: down, knock
         down, cut down, push down, pull down]

Moby Thesaurus II by Grady Ward, 1.0:

35 Moby Thesaurus words for "push down":
   bank, bear down, bring low, couch, crab, debase, depress, detrude,
   dip, downbear, feather, fishtail, haul down, indent, let down,
   loop, lower, plow, porpoise, press down, pull down, pull out,
   pull up, reduce, roll, sideslip, sink, skid, spin, spiral, stunt,
   take down, thrust down, undulate, yaw