Definition:Center


 * Analysis:
 * Center of a power series


 * Abstract Algebra:
 * Center of a group
 * Center of a ring


 * Geometry:
 * Center of a circle
 * Center of a sphere


 * Graph Theory:
 * Center of a tree

Linguistic Note
British English spells this centre.

The convention on is to use the American English spelling center, but it is appreciated that there may be lapses.