Buckle

A buckle is a metal or plastic fastener used to join the ends of a belt, strap, or shoe. As a verb, it can mean to fasten with a buckle or to bend and collapse under pressure.

From Old French “bocle,” meaning “buckle” or “ring,” from Latin “buccula,” “little cheek,” a diminutive of “bucca,” “cheek.” The link may be from curved shapes like cheek guards on armor.