idler.

1. A pulley, roller, or gear that guides, supports, or passes on motion without being the principal driver or output.

2. A person characterized as habitually doing little or avoiding work.

Use it for

Words that belong together

• an idler pulley
• an idler gear
• a belt idler

On the page

The idler pulley turned silently while the loaded shaft began to chatter.

An idler gear changed the direction of rotation without altering the overall ratio by itself.

Usage notes

Primary category: sci-fi. Forms: Singular idler; plural idlers. Legacy lexical fields mirror sense 1 only. Use numbered sense fields for all meanings.