Backlash
Pronunciation : Back"lash`
Part of Speech : n.
Etymology : [Back , adv. + lash.] (Mech.)
Definition : Defn: 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.
Source : Webster's Unabridged Dictionary, 1913