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Main form: centre or centre, noun.

Other forms: central (adjective), center/centre (verb)

Typical usage:

  • Something right in the middle, such as the center of a circle.
  • Something pivotal, crucial, a key ingredient.
  • A basin of attraction, something to which things get drawn.
  • The average.
  • In the middle, a compromise position, typically use for ideologies or viewpoints.
  • A source or point of origin, typically for something transmitted in all directions, such as light.
  • A facility providing a service.

Opposite words: periphery, boundary, endpoint.

Derived words: barycenter, epicenter, incenter, curcumcenter, excenter.


Typically used for an element or a subset in a set with additional structure, satisfying certain special core properties.

In group theory

Center of a group: The set of those elements of the group that commute with every element of the group. It forms a subgroup, in fact, a characteristic subgroup.

Primary subject wiki entry: Groupprops:Center

Also located at: Wikipedia:Center (group theory)

In ring theory

Center of a ring: The set of those elements of a (usually unital) ring that commute with every element of the ring. The center of a ring is a subring; for a unital ring, it is a subring containing the multiplicative identity.

Primary subject wiki entry: Noncommutative:Center of a ring

In graph theory

Center of a graph