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Word of the Day 3 September 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.

In use

Dial reads the same coming back, so we've picked up backlash in that leadscrew since the last check.

Written by our editors to show how the term is used, not a recorded quotation.

Sources

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