Concentric describes something, like circles, that have a common center.
Concentric is from the Latin word concentricus, from com ("together") plus centrum ("center" or "circle"). So, concentric things have a center in common. If you play darts, you aim for the smallest red dot of those colorful concentric circles. Although it's usually used to describe circles, ideas can also be concentric if they have a common point, such as when your dreams revolve around a concentric theme of flying. The opposite word is eccentric ("not having a common center") like that oddball neighbor you have nothing in common with.