Concentric describes circles or rings that share the same center point but have different sizes, like a target with its bullseye surrounded by larger and larger rings. If you drop a pebble into a calm pond, you'll see concentric ripples spreading outward, each circle perfectly centered on where the pebble hit the water.

Picture cutting a tree trunk: you'll see concentric rings showing each year of growth, all circling the same middle point. The lanes of a running track are concentric ovals. The layers of an onion form concentric layers.

Concentric is different from overlapping circles that just happen to touch. These circles must be nested inside each other, like a set of mixing bowls stacked together, all sharing that crucial center point. Architects use concentric designs in domed buildings like the U.S. Capitol. Ancient structures like Stonehenge have concentric circles of stones.

You might encounter this word in math class when studying geometry, or in science when learning about atomic structure, where electrons are sometimes shown in concentric shells around the nucleus. The opposite of concentric is eccentric, which can mean off-center or not sharing the same center point.