primum mobile

The story

1. Ancient Greek · derived fromτὸ πρῶτον κινῆσαν“prime mover”
2. Arabic · calque ofمُحَرِّك أَوَّل“first mover”
3. Medieval Latin · derived fromprīmum mōbile
4. Middle English · inherited fromprimum mobile“outermost celestial sphere causing other spheres to move”
5. English todayprimum mobile

From Middle English primum mobile (“outermost celestial sphere causing other spheres to move”), borrowed from Medieval Latin prīmum mōbile (literally “first mover”), a calque of Arabic مُحَرِّك أَوَّل (muḥarrik ʔawwal, “first mover”), which is itself a calque of Ancient Greek τὸ πρῶτον κινῆσαν (tò prôton kinêsan, “prime mover”).