n. Anything that floors or upsets a person, as a blow that knocks him down; a conclusive answer or retort; a task that exceeds one's abilities. [ Colloq. ] [ 1913 Webster ]
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 ]