A pothole (sometimes called kettle) is a type of disruption in the surface of a roadway where a portion of the road material has broken away, leaving a hole. They are typically formed due to the freezing and thawing of water that has seeped into the surface, which expands when frozen. Automobiles that travel over the weakened roadway can break off small pieces. Potholes tend to become most apparent during spring months due to daily freeze-thaw cycles and general difficulty of repairing potholes in cold weather.
The number of potholes that appear in any particular stretch of roadway largely depends on the type of pavement used. Surfaces that absorb less water are generally less susceptible to the problem.
Potholes can reach feet in width, though they usually only become a few inches deep, at most. If they become large enough, damage to tires and vehicle suspensions can occur.
See also
There is also a geological formation known as a pothole, very basically an unusual form of cave.
There is also a formation in rivers called a pothole caused by a whirlpool eroding a hole into rock.