01 n. The nucleus or central part of the earth, forming most of its mass; -- disting. from lithosphere, hydrosphere, etc.
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1.
The nucleus or central part of the earth, forming most of its mass; -- disting. from lithosphere, hydrosphere, etc.(Geol.)
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2.
The central mass of an aster from which the rays extend and within which the centrosome lies when present; the attraction sphere. The name has been used both as excluding and including the centrosome, and also to designate a modified mass of protoplasm about a centrosome whether aster rays are developed or not.(Biol.)