Source : Webster's Revised Unabridged Dictionary (1913)

Concentric \Con*cen"tric\, Concentrical \Con*cen"tric*al\, a.
   [F. concentrique. See {Concenter}.]
   Having a common center, as circles of different size, one
   within another.

         Concentric circles upon the surface of the water. --Sir
                                                  I. Newton.

         Concentrical rings like those of an onion. --Arbuthnot.

Concentric \Con*cen"tric\, n.
   That which has a common center with something else.

         Its pecular relations to its concentrics. --Coleridge.

Source : WordNet®

concentric
     adj : having a common center; "concentric rings" [syn: {concentrical},
            {homocentric}] [ant: {eccentric}]