Ridged means having raised lines or strips running across a surface, like the pattern you see on corduroy pants or the roof of your mouth. If you run your finger along something ridged, you'll feel bumps and grooves alternating in a regular pattern.

Potato chips are often ridged, with parallel lines pressed into them that make them crunchier and better at holding dip. The soles of hiking boots have deep ridges that grip mud and rocks. Seashells, tree bark, and even your fingertips have ridges.

A ridged surface has many small ridges running parallel to each other, like tiny mountain ranges side by side. When something is ridged, it's usually stronger or has better grip than if it were smooth: ridged cardboard resists crushing better than flat cardboard, and ridged bike tires grip the road more securely than slick ones.