buckle

noun

• a flat, typically rectangular frame with a hinged pin, used for joining the ends of a belt or strap.
• a similarly shaped ornament, especially on a shoe.

verb

• 1 [with object] fasten or decorate with a buckle:he buckled his belt
• [no object] (buckle up) fasten one’s seat belt in a car or aircraft.

• 2 [no object] bend and give way under pressure or strain:the earth buckled under the titanic stress

  [from French boucler 'to bulge']
• [with object] bend (something) out of shape:a giant oak buckles the sidewalk
• (of a person) yield or collapse under pressure:a weaker person might have buckled under the strain