primummobile

pri·mum mo·bi·le (prīʹməm mōʹbə-lē', prēʹməm mōʹbĭ-lā') n.

1. The tenth and outermost concentric sphere of the universe thought in Ptolemaic astronomy to revolve around the earth from east to west in 24 hours and believed to cause the other nine spheres to revolve with it.

2. See prime mover.

  [Medieval Latin prīmum mōbile: prīmum, neuter of prīmus, first + mōbile, from neuter of mōbilis, movable (translation of Arabic al-muḥarrik al-’awwal: al-, the + muḥarrik, mover + ’awwal, first).]

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