—n. 1. a clasp consisting of a rectangular or curved rim with one or more movable tongues, fixed to one end of a belt or strap, used for fastening to the other end of the same strap or to another strap.
2. any similar contrivance used for such purposes.
3. an ornament of metal, beads, etc., of similar appearance.
4. a bend, bulge, or kink, as in a board or saw blade.
—v.t. 1. to fasten with a buckle or buckles: Buckle your seat belt. 2. to shrivel, by applying heat or pressure; bend; curl.
3. to prepare (oneself) for action; apply (oneself) vigorously to something.
4. to bend, warp, or cause to give way suddenly, as with heat or pressure.
—v.i. 1. to close or fasten with a buckle: Grandmother always wore shoes that buckled. 2. to prepare oneself or apply oneself: The student buckled to the lesson. 3. to bend, warp, bulge, or collapse: The bridge buckled in the storm. 4. to yield, surrender, or give way to another (often fol. by under): She refused to take the medicine, but buckled under when the doctor told her to. 5. buckle down, to set to work with vigor; concentrate on one's work: He was by nature a daydreamer and found it hard to buckle down. 6. buckle up, to fasten one's belt, seat belt, or buckles: She won't start the car until we've all buckled up.