central(n = noun.artifact) exchange, telephone exchange - a workplace that serves as a telecommunications facility where lines from telephones can be connected together to permit communication;
Derived form adjective central₂

1.  central(s = adj.all) cardinal, fundamental, key, primal - serving as an essential component; "a cardinal rule"; "an example that was fundamental to the argument"; "computers are fundamental to modern industrial structure"; "the central cause of the problem"
Derived form noun center₅, noun center₆

2.  central(a = adj.all) - in or near a center or constituting a center; the inner area; "a central position"
Antonym: peripheral
Derived form noun center₁, noun center₄, noun central₁, noun centrality₁

   Relating to the center; situated in or near the center or middle; containing the center; of or pertaining to the parts near the center<-- original had "or of.." -->; equidistant or equally accessible from certain points. [1913 Webster]

   The central, or one of the central, bones of the carpus or or tarsus. In the tarsus of man it is represented by the navicular. [1913 Webster]

central, adj.
1 of, at, or forming the centre.
2 from the centre.
3 chief, essential, most important.

Idiom:
Central America the isthmus joining North and South America. central bank a national bank issuing currency etc. central heating a method of warming a building by pipes, radiators, etc., fed from a central source of heat. central nervous system Anat. the complex of nerve tissues that controls the activities of the body, in vertebrates the brain and spinal cord. central processor (or processing unit) the principal operating part of a computer.

Derivative:
centrality n. centrally adv.

Etymology:
F central or L centralis f. centrum CENTRE

N  middle, midst, mediety, mean, medium, middle term, center &c, mid-course, mezzo termine, juste milieu, halfway house, nave, navel, omphalos, nucleus, nucleolus, equidistance, bisection, half distance, equator, diaphragm, midriff, intermediate, middle, medial, mesial, mean, mid, median, average, middlemost, midmost, mediate, intermediate, equidistant, central, mediterranean, equatorial, homocentric, in the middle, midway, halfway, midships, amidships, in medias res.

N  centrality, centricalness, center, middle, focus, core, kernel, nucleus, nucleolus, heart, pole axis, bull's eye, nave, navel, umbilicus, backbone, marrow, pith, vertebra, vertebral column, hotbed, concentration, centralization, symmetry, center of gravity, center of pressure, center of percussion, center of oscillation, center of buoyancy, metacenter, central, centrical, middle, azygous, axial, focal, umbilical, concentric, middlemost, rachidian, spinal, vertebral, middle, midst, centrally.