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primum mobile definition

pri·mum mo·bile (prī′məm mō′bə lē′)

Astron. in the Ptolemaic system, the tenth and outermost concentric sphere, revolving from east to west around the earth and causing all celestial bodies to revolve with it

Etymology: ML, first movable thing: see prime, & mobile

Webster's New World College Dictionary Copyright © 2009 by Wiley Publishing, Inc., Cleveland, Ohio.
Used by arrangement with John Wiley & Sons, Inc.

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