cen|tro|sphere «SEHN truh sfihr», noun.
1. Biology. the mass of protoplasm around a centriole in a centrosome, from which the aster rays radiate; the astrosphere: »
When present, the centrosphere takes a conspicuous though probably unimportant part in cell division (A. Franklin Shull).
2. Geology. the central core of the earth.
Useful english dictionary. 2012.