A sudden backward motion.

A negative reaction, objection or outcry, especially of a violent or abrupt nature.

"The public backlash to the proposal was quick and insistent."

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.

The jarring or reflex motion caused in badly fitting machinery by irregularities in velocity or a reverse of motion.

To cause or set off a backlash.