Inflexibility is the quality of being rigid, unable to bend, or unwilling to change. When something is inflexible, it won't adapt to new situations or circumstances.

The word applies to both physical objects and attitudes. A metal rod has inflexibility: it won't bend or flex when you push on it. But inflexibility more often describes how people think or act. A teacher showing inflexibility might refuse to adjust a deadline even when half the class got sick, or insist on following a lesson plan even when students clearly don't understand the material.

Inflexibility becomes a problem when conditions change but someone refuses to change with them. Imagine planning an outdoor birthday party with complete inflexibility: you'd insist on having it outside even if a thunderstorm rolled in, rather than moving it indoors. That kind of inflexibility turns what could be a small adjustment into a disaster.

The opposite is flexibility, the ability to bend and adapt. While some rules need inflexibility (like safety rules), most situations benefit from flexibility. A soccer coach with too much inflexibility might never adjust their strategy, even when it's clearly not working. Being flexible doesn't mean having no standards or plans; it means being smart enough to adjust them when necessary.