For the English historian, see Henry Thomas Buckle

A buckle is a clasp used for fastening two things together, such as the ends of a belt, or for retaining the end of a strap. Before the invention of the zipper, buckles were commonly used to fasten boots and other shoes.

A buckle can refer to a seat belt or safety belt, as in the term, "buckle up ."

In Canadian heraldry, a buckle is the brisure of an eighth daughter.

As a verb, to buckle is to distort under physical compression. Buckling often leads to sudden and complete collapse of a structure. Buckling is used also metaphorically, of people who react suddenly and adversely to stress.

See also: turnbuckle.