BACKLASH n.
The distance through which one part of connected machinery, as a wheel, piston, or screw, can be moved without moving the connected parts, resulting from looseness in fitting or from wear; also, the jarring or reflex motion caused in badly fitting machinery by irregularities in velocity or a reverse of motion.…
BEARING n.
situation of one object, with respect to another, such situation being supposed to have a connection with the object, or influence upon it, or to be influenced by it; hence, relation; connection. But of this frame, the bearings and the ties, The strong connections, nice dependencies. Pope.