An Idler

1. One who idles; one who spends his or her time in inaction.
2. One who idles; a lazy person; a sluggard.
3. (nautical, dated) Any member of a ship's crew who is not required to keep the night-watch^[1]
4. A mechanical device such as a pulley or wheel that does not transmit power, but supports a moving belt etc.^[