(n.) The center of mass, inertia, or gravity of a body or system of bodies.

Bund Rochdale cooperative air line alliance anthrophore arbor assemblage association axle axle bar axle shaft axle spindle axle-tree band bearing beeline bloc body bole cane carpophore caudex caulicle caulis center center of action center of gravity centroid centrum chord coalition college combination combine common market confederacy confederation consumer cooperative cooperative cooperative society core corps council credit union culm customs union dead center diagonal diameter direct line directrix distaff economic community edge epicenter federation footstalk free trade area fulcrum funicule funiculus gang gimbal great-circle course group grouping gudgeon haulm heart hinge hingle horizontal axis hub kernel leafstalk league machine mandrel marrow medulla metacenter middle mob nave navel normal nub nucleus oarlock omphalos partnership pedicel peduncle perpendicular petiole petiolule petiolus pin pintle pith pivot pole political machine radiant radius radius vector reed rest resting point right line ring rowlock secant seedstalk segment shortcut side society spear spindle spire stalk stem stipe stock storm center straight straight course straight line straight stretch straightaway straw streamline swivel tangent thole tholepin tigella transversal trunk trunnion umbilicus union vector yaw