CONCENTRIC
, having the same centre. It is opposed to excentric, or having different centres.
The word is chiefly used in speaking of round bodies and figures, such as circular, and elliptic ones; but it may likewise be used for polygons that are drawn parallel to each other, from the same centre.
Nonnius's method of graduating instruments consists in describing with the same quadrant 45 concentric arches, dividing the outermost into 90 equal parts, the next into 89, and so on.