dusty
Covered with a layer of fine, powdery dirt or dust.
Dusty means covered with dust, those tiny particles of dirt, pollen, dead skin, and other materials that settle on surfaces everywhere. A dusty bookshelf hasn't been cleaned in a while, and when you run your finger across it, you'll see the grayish powder that's accumulated. Attics, basements, and old barns are often dusty places because air doesn't circulate much there, giving dust plenty of time to settle undisturbed.
The word can also describe something very dry or powdery in texture. A dirt road on a hot summer day might kick up dusty clouds with every footstep or passing car. In baseball, players slide into a base and emerge covered in the dusty infield dirt.
Beyond the literal meaning, people sometimes use dusty to describe ideas, skills, or knowledge that haven't been used in a long time. If your math skills are a bit dusty, it means you haven't practiced in a while and might need to review before that test. When historians discover a dusty old manuscript in an archive, they've found something forgotten or neglected that might contain valuable information. Something dusty, whether an object or an idea, has been sitting idle, waiting for someone to shake off that layer of time and put it back to use.