Definition of belt noun from the Oxford Advanced Learner's Dictionary

belt

noun

belt

1 a long narrow piece of leather, cloth, etc. that you wear around the waistto do up/fasten/tighten a belta belt buckle see also black belt, lifebelt, seat belt, suspender belt2 a continuous band of material that moves round and is used to carry things along or to drive machinery see also conveyor belt, fan belt3 an area with particular characteristics or where a particular group of people livethe country's corn/industrial beltWe live in the commuter belt.a belt of rain moving across the country see also green belt4 (informal) an act of hitting something/somebody hardShe gave the ball a terrific belt.

Idioms

below the belt

(of a remark) unfair or cruelThat was distinctly below the belt!

belt and braces

(informal) taking more actions than are really necessary to make sure that something succeeds or works as it shoulda belt-and-braces policy

have something under your belt

(informal) to have already achieved or obtained somethingShe already has a couple of good wins under her belt.

more at tighten your belt at tighten