idler

Short definition from Wiktionary

Noun

1. 1
   One who idles; one who spends their time in inaction.
2. 2
   One who idles; a lazy person; a sluggard.
3. 3
   Any member of a ship's crew who is not required to keep the night-watch.
4. 4
   A mechanical device such as a pulley or wheel that does not transmit power through its own axle, but forms part of a gear train, supports a moving belt, etc.

Adjective

1. 1
   comparative form of idle: more idle