center (nom)
Sens 1 : a point around which things revolve; often : a focal point for
attraction, concentration, or activity : a point, area, person, or thing that is most important
or pivotal in relation to an indicated activity, interest, or condition. [source : MWU]
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Sens 2 : the point at an average distance from the exterior angles, points, or
lines of a figure or body. [source : MWU]
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Sens 3 : a source from which something originates. [source : MW]
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Sens 4 : the middle part. [source : MW]