- In the Ptolemaic system, the outermost of the
revolving concentric spheres constituting the universe, the motion of
which was supposed to carry with it all the inclosed spheres with their
planets in a daily revolution from east to west. See Crystalline
heavens, under Crystalline.
Meaning of 'primum mobile' (Princeton's WordNet)
1 . primum mobile
[ n]
Meaning (1): - an agent that is the cause of all things but does not itself have a cause