D defs.my
Entry 3 senses Webster, 1913

Backlash

/(băk"lăsh`)/ · Back·lash · IPA /ˈbækˌlæʃ/
01 n. The distance through which one part of connected machinery, as a wheel, piston, or screw, can be moved without moving the connected parts, …
  1. 1.
    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.(Mech.)
  2. 2.
    A strong and sudden reverse movement in a moving part of a machine.
  3. 3.
    A strong popular reaction serving to counter the effect of an action; -- used especially of adverse reactions to social or political developments.