I enjoy looking up basic words in the dictionary. You know, words so basic that you don't even stop to think about how to define them because you understand the concept so innately. Most of these words have more complicated definitions than you would think. On Dictionary.com, "wheel" has 29 definitions (including idioms). It starts with...
1. a circular frame or disk arranged to revolve on an axis, as on or in vehicles or machinery.
2. any machine, apparatus, instrument, etc., shaped like this or having a circular frame, disk, or revolving drum as an essential feature: a potter's wheel; roulette wheel; spinning wheel. (continue?)