idler

/ˈaɪdlər/
noun
  1. A person who avoids work or spends time doing nothing.
    • The town was full of idlers sitting on benches all day.
    • He was known as an idler who never held a job for more than a month.
    • My grandmother called me an idler for lying in bed until noon.
  2. A wheel or gear that transmits motion between two other wheels or gears, often used to change direction or tension.
    • The idler pulley helps keep the belt tight in the lawnmower.
    • The mechanic replaced the idler in the engine's belt system.
    • A broken idler gear caused the machine to stop working.
Antonyms
What does "idler" mean? | whatsthatwordmean | whatsthatwordmean