idle

Concise Oxford English Dictionary © 2008 Oxford University Press:
idle/ˈʌɪdl/

▶adjective (idler, idlest)

• 1 avoiding work; lazy.

  ■ not working or in use.

• 2 having no purpose or basis: idle threats.

• 3 (of money) held in cash or in accounts paying no interest.

▶verb

• 1 spend time doing nothing.

  ■ move aimlessly.

  ■ N. Amer. take out of use or employment.

• 2 (of an engine) run slowly while disconnected from a load or out of gear.

– derivatives
idleness noun,
idly adverb.

– origin OE īdel ‘empty, useless’, of W. Gmc origin.