What is the term that describes the bending of rock layers due to stress?

In geology, the term "fold" or "folding" refers to the bending of rock layers due to stress. Most often, large folds are a result of some type of major collision.

When a rock formation experiences significant stress, the formation typically either folds or faults. Folding refers to the rock formation bending either in a syncline formation or an anticline formation. A syncline formation is concave up and resembles a "U" shape, while an anticline formation is concave down and resembles an "A" shape. The stress that forms folding in rocks is typically caused by a strong force placed on the rock formation.