The Collaborative International Dictionary of English v.0.48:

floored \floored\ adj.
   1. provided with a floor. ceilinged
      [WordNet 1.5]

   2. knocked down to the floor or ground.
      [PJC]

   3. defeated; overwhelmed.
      [PJC]

   4. suprised and confounded; nonplused; as, I was floored by
      the brilliance of the solution.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

Floor \Floor\, v. t. [imp. & p. p. Floored; p. pr. & vb. n.
   Flooring.]
   1. To cover with a floor; to furnish with a floor; as, to
      floor a house with pine boards.
      [1913 Webster]

   2. To strike down or lay level with the floor; to knock down;
      hence, to silence by a conclusive answer or retort; as, to
      floor an opponent.
      [1913 Webster]

            Floored or crushed by him.            --Coleridge.
      [1913 Webster]

   3. To finish or make an end of; as, to floor a college
      examination. [Colloq.]
      [1913 Webster]

            I've floored my little-go work.       --T. Hughes.
      [1913 Webster]

WordNet (r) 3.0 (2006):

floored
    adj 1: provided with a floor [ant: ceilinged]

Moby Thesaurus II by Grady Ward, 1.0:

105 Moby Thesaurus words for "floored":
   addled, all up with, armored, at a loss, baffled, bamboozled, beat,
   beaten, bested, buffaloed, cased, ceiled, cloaked, clouded, coated,
   confounded, coped, covered, covert, cowled, curtained, dazed,
   defeated, discomfited, done for, done in, down, eclipsed,
   encapsulated, encapsuled, encased, enveloped, enwrapped, fallen,
   filmed, fixed, fuddled, hooded, hors de combat, housed,
   in a dilemma, in suspense, lambasted, lathered, licked, loricate,
   loricated, mantled, masked, muddled, muffled, mystified,
   nonplussed, obscured, occulted, on tenterhooks, on the skids,
   outdone, overborne, overcome, overmastered, overmatched,
   overpowered, overridden, overthrown, overturned, overwhelmed,
   packaged, panicked, paved, perplexed, put to rout, puzzled,
   roofed-in, routed, ruined, scattered, screened, scummed, settled,
   sheathed, shelled, shielded, shrouded, silenced, skinned,
   skinned alive, stampeded, stuck, stumped, swathed, tented, thrown,
   trimmed, trounced, under cover, undone, upset, veiled, walled,
   walled-in, whelmed, whipped, worsted, wrapped