backlash
The play or clearance between mating components, especially gears, which causes a delay or lost motion when the direction of movement is reversed.
In engineering, backlash is the physical 'slop' or gap between gear teeth. When you turn a gear clockwise, then suddenly turn it counterclockwise, there is a tiny moment where the teeth aren't touching; that gap is backlash. In general English, it has been metaphorically extended to mean a strong negative reaction.
Word relationships
- play: 'Play' is a general term for any looseness or clearance in a mechanism, while 'backlash' specifically refers to the lost motion between mating parts upon reversal.
- interference fit: An interference fit is a tight connection where parts are pressed together with no clearance, completely eliminating any play or backlash.
Commonly confused with
- recoil: Recoil is the backward spring or kickback of a device after firing or releasing energy, whereas backlash is the passive clearance gap between parts.
Word family
- backlashed (verb): Experienced a sudden backward movement or play.
Collocations
- eliminate backlash
- backlash compensation
- gear backlash
- anti-backlash
Example sentences
- "The milling machine features ball screws with zero backlash, ensuring extreme accuracy when cutting complex metal parts." A review of a high-precision CNC machine
- "Excessive backlash in the steering gear made the car feel unresponsive and drift slightly on the highway." An automotive steering diagnostic
Memory hook
Think of a whip 'lashing' 'back'. When gears reverse, they 'lash' back against each other across the empty gap. Backlash is the gap where motion gets lost.
When not to use
Do not use backlash to describe general looseness in a single part; it specifically refers to the clearance gap between mating parts when motion is reversed.
Fun facts
- Astronomical telescopes use highly specialized 'anti-backlash' gears because even a microscopic amount of play would cause the telescope to miss stars millions of light-years away.
- The metaphorical use of 'backlash' (social reaction) is now far more common in daily speech than its original mechanical engineering definition.
Explore more words
Our English vocabulary app: FSRS spaced repetition, 5,000+ curated words across 119 topic groups, CEFR A1 to C2. Explore your mastery with the beautiful Vocabulary World feature.