<p><strong>Noun</strong></p><ul><li>a sudden, forceful backward movement; recoil</li><li>a strong or violent reaction, as to some social or political change: a backlash of angry feeling among Southern conservatives within the party</li><li>Machinery: the space between the thickness of a gear tooth and the width of the space between teeth in the mating gear, designed to allow for a film of lubricant, binding from heat expansion and eccentricity, or manufacturing inaccuracies</li><li>play or lost motion between loosely fitting machine parts</li><li>Angling: a snarled line on a reel, usually caused by a faulty cast</li></ul><p><strong>Verb</strong></p><ul><li>(used without object) to make or undergo a backlash</li></ul>