n. 25B6; noun a belt buckle : CLASP, clip, catch, hasp, fastener.
25B6; verb
he buckled the belt round his waist : FASTEN, do up, hook, strap, secure, clasp, clip.
the front axle buckled : WARP, bend, twist, curve, distort, contort, deform; bulge, arc, arch; crumple, collapse, give way.
25A0; buckle down GET (DOWN) TO WORK, set to work, get down to business; work hard, apply oneself, make an effort, be industrious, be diligent, focus; informal pull one's finger out; Brit. informal get stuck in.