primum mobile (n.)youdaoicibaDictYouDict[primum mobile 词源字典]
"the first source of motion," mid-15c., from Medieval Latin (11c.), literally "the first movable thing;" see prime (adj.) + mobile. A translation of Arabic al-muharrik al-awwal "the first moving" (Avicenna).[primum mobile etymology, primum mobile origin, 英语词源]