geniusyoudaoicibaDictYouDict[genius 词源字典]
genius: [16] Latin genius originally meant ‘deity of generation and birth’. It came ultimately from the Indo-European base *gen- ‘produce’ (source of English gene, generate, genitive, etc), probably via a derivative *gnjos. It broadened out considerably in meaning, initially to ‘attendant spirit’, the sense in which English originally acquired it (French took it over as génie, a word which, because of its phonetic and semantic similarity to Arabic jinn, 18th-century translators of the Arabian nights eagerly adopted into English as genie).

The main modern English sense, ‘person of outstanding intellectual ability’, which dates from the 17th century, goes back to a comparatively rare Latin ‘intellectual capacity’. Genial [16] comes from Latin geniālis, a derivative of genius, which again originally meant ‘of generation and birth’ (a sense which survived into English: ‘And thou, glad Genius! in whose gentle hand the bridal bower and genial bed remain’, Edmund Spenser, Epithalamion 1595).

It later developed in Latin to ‘pleasant, festive’.
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genius (n.)youdaoicibaDictYouDict
late 14c., "tutelary or moral spirit" who guides and governs an individual through life, from Latin genius "guardian deity or spirit which watches over each person from birth; spirit, incarnation; wit, talent;" also "prophetic skill," originally "generative power" (or "inborn nature"), from PIE *gen(e)-yo-, from root *gene- "to produce, give birth, beget" (see genus). Sense of "characteristic disposition" of a person is from 1580s. Meaning "person of natural intelligence or talent" and that of "exalted natural mental ability" are first recorded 1640s.