The point in the interior of a circle that is equidistant from all points on the circumference. • The point in the interior of a sphere that is equidistant from all points on the circumference. • The middle portion of something; the part well away from the edges. • The innermost point of the Earth, or the Earth itself, as the center or foundation of the Universe; the center or foundation of the Universe abstractly. • The point on a line that is midway between the ends. • The point in the interior of any figure of any number of dimensions that has as its coordinates the arithmetic mean of the coordinates of all points on the perimeter of the figure (or of all points in the interior for a center of volume). • A point on a triangle's plane that is in some sense in its middle. • A place, especially a building or complex, set aside for some specified function or activity. • The ensemble of moderate or centrist political parties. • The venue in which the head of government in a centralized state is situated. • A topic that is particularly important in a given context, the element in a subject of cognition, volition or discussion that is perceived as decisive. • A player in the middle of a playing area. • The player, generally the tallest, who plays closest to the basket. • The forward that generally plays between the left wing and right wing and usually takes the faceoffs. • The person who holds the ball at the beginning of each play. • A player who can go all over the court, except the shooting circles. • A pass played into the centre of the pitch. • One of the backs operating in a central area of the pitch, either the inside centre or outside centre. • A certain mechanical implement functioning in the middle of a whole apparatus • A temporary structure upon which the materials of a vault or arch are supported in position until the work becomes self-supporting. • One of the two conical steel pins in a lathe, etc., upon which the work is held, and about which it revolves. • A conical recess or indentation in the end of a shaft or other work, to receive the point of a center, on which the work can turn, as in a lathe. • The ring in the gambling game two-up in which the spinner operates. • The set of those elements (of a given algebraic structure) that commute with every other element, usually denoted Z(G). In the case of (semi-)groups, it is required that they commute under the (semi-)group operation; in the case of rings and (Lie) algebras, under multiplication (i.e. the bracket for Lie algebras)