WordNet (r) 3.0 (2006):

knock over
    v 1: cause to overturn from an upright or normal position; "The
         cat knocked over the flower vase"; "the clumsy customer
         turned over the vase"; "he tumped over his beer" [syn:
         overturn, tip over, turn over, upset, knock over,
         bowl over, tump over]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "knock over":
   beat down, blow down, bowl over, break down, bring down, bulldoze,
   burn down, cast down, chop down, commit robbery, cut down, down,
   drop, fell, flatten, floor, ground, heist, hijack, hold up, knock,
   knock down, level, mow down, mug, prostrate, pull down, rase, raze,
   rip off, rob, smash, steamroller, stick up, take down, tear down,
   throw down