The corkscrew is a roller coaster inversion which most often resembles a loop that has been 'widened' in terms of the element's entrance and exit points being a distance away from each other.
It was named due to its resemblance to a the corkscrew tool used to remove corks from bottles. Riders enter the corkscrew element and are transported significantly to the left or right while being flipped upside down 360 degrees.
Corkscrew is also the name of several roller coasters, including a three-loop coaster at Valleyfair in Shakopee, Minnesota. Until the hypercoaster "Wild Thing" (the fifth highest and fastest roller coaster in the world at the time it opened) opened in 1996, Corkscrew was the only outdoor all-steel roller coaster in Minnesota.