A fulcrum is defined as the point or support on which a lever pivots. I always associate it with classical physics, probably because of Archimedes’ famous boast: "Give me a place to stand and with a lever I will move the whole world." That place to stand would have been his fulcrum.
However, according to the origin of the word, Archimedes could have saved his energy and stayed in bed. The Latin verb fulcire meant to support or prop up, which fits in nicely with the fulcrum/lever image.
But when the noun fulcrum developed from that verb, it had a quite specific meaning. It meant a bed post or foot. There were usually four of them, and their function was to raise the bed from the drafty floor.
(substitute @ for AT above)