if an engine idles, it runs slowly while the vehicle, machine etc is not moving:
He flicked a switch and let the boat idle.
to spend time doing nothing:
Sometimes he went for a walk; sometimes he just idled.
3 [transitive] American English
to stop using a factory or stop providing work for your workers, especially temporarily [= shut down]:
The company has indefinitely idled a number of its US plants.
idle something ↔ awayphrasal verb
They idled their time away in the pub.