A buckle is a clasp or fastener, such as the one on the end of a belt. In the old days, not only belts but also shoes had buckles.

When you fasten your belt buckle, you can say you buckle it — you also buckle your seat belt and buckle a kid's bike helmet under his chin. When the ground buckles during an earthquake, it folds or bends out of shape, and when your knees buckle, you could fall. You might also buckle under pressure or stress. The Latin root word is buccula, "cheek strap of a helmet."

Definitions of buckle
  1. noun
    fastener that fastens together two ends of a belt or strap; often has loose prong
    see moresee less
    belt buckle
    the buckle used to fasten a belt
    type of:
    fastener, fastening, fixing, holdfast
    restraint that attaches to something or holds something in place
  2. verb
    fasten with a buckle or buckles
    synonyms: clasp
    see moresee less
    undo the buckle of
    type of:
    fasten, fix, secure
    cause to be firmly attached
  3. verb
    bend out of shape, as under pressure or from heat
    “The highway buckled during the heat wave”
    synonyms: heave, warp
    see moresee less
    rise upward, as from pressure or moisture
    type of:
    change surface
    undergo or cause to undergo a change in the surface
  4. verb
    fold or collapse
    “His knees buckled
    synonyms: crumple
    see moresee less
    type of:
    break, cave in, collapse, fall in, founder, give, give way
    break down, literally or metaphorically
  5. verb
    consent reluctantly
    synonyms: buckle under, give in, knuckle under, succumb, yield
    see moresee less
    accede, bow, defer, give in, submit
    yield to another's wish or opinion
    type of:
    accept, consent, go for
    give an affirmative reply to; respond favorably to
  6. noun
    a shape distorted by twisting or folding
    synonyms: warp
    see moresee less
    type of:
    distorted shape, distortion
    a shape resulting from distortion
Word Family

Test prep from the experts

Boost your test score with programs developed by Vocabulary.com’s experts.

  • Proven methods: Learn faster, remember longer with our scientific approach.
  • Personalized plan: We customize your experience to maximize your learning.
  • Strategic studying: Focus on the words that are most crucial for success.


  • Number of words: 500+
  • Duration: 8 weeks or less
  • Time: 1 hour / week


  • Number of words: 500+
  • Duration: 10 weeks or less
  • Time: 1 hour / week


  • Number of words: 700+
  • Duration: 10 weeks
  • Time: 1 hour / week