Definitions
1.NounA long sled without runners, with the front end curled upwards, which may be pulled across snow by a cord or used to coast down hills.
2.NounA similar sled of wood, pulled by dogs, possibly with steel runners, made to transport cargo.
3.NounSomething which, once it starts going (figuratively) downhill, is unstoppable until it reaches the bottom.
4.NounA knit cap, designed to provide warmth in cold weather.
5.VerbTo slide down a hill on a toboggan or other object.
6.VerbTo go downhill unstoppably until one reaches the bottom.
7.VerbTo fly sharply downward so as to build up speed to facilitate in-flight refueling of a faster aircraft.