'Concentricity' definitions:

Definition of 'concentricity'

(from WordNet)
noun
The quality of having the same center (as circles inside one another) [ant: eccentricity]

Definition of 'Concentricity'

From: GCIDE
  • Concentricity \Con`cen*tric"i*ty\, n. The state of being concentric. [1913 Webster]