Definitions
1.NounA suddenly reversed or backward motion, such as of a rope or elastic band when it snaps under tension.
2.NounA negative reaction, objection or outcry, especially of a violent or abrupt nature."The public backlash to the proposal was quick and insistent."
3.NounThe looseness through which one part of connected machinery, such as a wheel, gear, piston, or screw, can be moved without moving the connected parts, or a measurement of the distance moved thereby; either intentional (as allowance) or unintentional (from error or wear).Wagon wheel structure showing felk
4.NounThe jarring or reflex motion caused in badly fitting machinery by irregularities in velocity or a reverse of motion.
5.VerbTo perform a backlash, to lash back in reaction to some cause.