Durability is the ability of something to last a long time and withstand wear, damage, or repeated use without breaking down. A backpack with good durability can handle years of being stuffed with books, tossed on the ground, and dragged through hallways. A durable bicycle keeps working smoothly even after countless rides through rain, mud, and rough terrain.

When you're shopping for something important, durability matters: cheap sneakers might fall apart after a few weeks, while durable ones last for months of playground action. Engineers test the durability of bridges, phones, and cars to make sure they'll hold up over time.

Durability applies to both physical objects and abstract things. A durable friendship lasts through disagreements and distance. A durable idea keeps proving useful year after year. The opposite of durable is fragile or flimsy: things that break easily or wear out quickly. When something has excellent durability, you can depend on it to keep working when you need it most.