Word of the Day 14 May 2026

backlash

The 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).

Why this one

Lost motion when a drive reverses. Some is deliberate, for lubrication and thermal growth. It is the change over time that matters.