In current English a genie is a supernatural being, usually imagined in human form, who appears when called and carries out the wishes of whoever holds the lamp, ring, or bottle that binds it. The same noun also stands, in more careful use, for a jinni: one of the jinn of Islamic and older Arabian belief, creatures able to remain unseen or to take animal or human shape. Ordinary speech favors the first picture. Figurative talk about letting the genie out of the bottle treats that picture as a force that, once freed, is hard to shut away.
The origin of the word genie is a borrowing from French, not a native English formation, and the lamp is a later overlay on that loan.
A French word with a Latin root
French génie is a learned take on Latin genius. In Roman religion a genius was the attendant spirit thought to watch over a person from birth, and also the inborn character of a household or a place. The Latin noun belongs with gignere, to beget, and with an Indo-European set of birth and kinship words. English kin, kind, generate, gender, and genius itself sit on that same root. French kept several of the Latin meanings: a guardian spirit, a person's bent, exceptional talent, and, later, a corps of military engineers.
English adopted génie as genie in the seventeenth century. Standard references disagree on the first English date because they are not always counting the same sense. The Oxford English Dictionary quotes a 1611 translation that uses Genie for a guardian spirit of France. Other etymologies put the tutelary-spirit sense in the 1650s. Merriam-Webster gives 1706 as first known use, the year an English version of Antoine Galland's French Arabian Nights applied genies to the spirits of those stories. The spread of dates is a bookkeeping difference, not evidence of two unrelated English words.
Where Arabic jinnī comes in
The sense that survived is a translator's match, not a shared ancestor. From 1704 to 1717 Galland issued Les Mille et Une Nuits. He chose French génie for Arabic jinnī, the singular that corresponds to the collective jinn. The words sounded alike, and both named beings that stand between the human world and the divine. English followed the French. The Oxford record of the jinn sense begins in 1706, in that English Galland, with hostile spirits already called genies. Another widely cited chronology places the Arabic-spirit sense in English prose in 1748. Either way, the eighteenth-century Nights locked a Latin-French spelling onto a being whose Arabic name is not descended from genius.
Arabic jinn is a collective noun. The ordinary singular is jinnī, which English has also spelled jinni, jinnee, and djinni. The Semitic root j-n-n has a core idea of hiding or covering. Related Arabic vocabulary includes majnūn, possessed or insane, jannah, a garden or paradise, and janīn, an embryo: things concealed, overgrown, or not yet in view. Mainstream English etymology treats the likeness of jinn to Latin genius as accidental. Some historians of religion have suggested contact with the Roman genius, with Aramaic ginnaya, a tutelary figure, or with an Iranian spirit-name. Those proposals remain contested, and the further origin of the Arabic word is unsettled. Readers who want a closer loan already have jinn and djinn; genie is the French dressing of the same idea.
How English split genie from genius
For a stretch the two English nouns overlapped. Early genie could mean a tutelary spirit and, more rarely, a person's disposition or a gifted person. Those uses faded as genius took the talent meanings and as the Nights took the spirit. The plural still shows the fork: genies is the everyday English form; genii copies the Latin plural of genius and is sometimes used for either word.
What English speakers now picture is a further narrowing of the Nights themselves. Two plots did most of the work. In the fisherman's tale a spirit is released from a vessel and then tricked back inside. In the tale of Aladdin, which Galland took from an oral informant rather than from his principal Arabic manuscript, spirits bound to a ring and a lamp serve whoever holds the object. Later retellings, theatre, and film kept the servant of the lamp and left behind most of the wider jinn lore: a created order of beings, morally accountable, neither simply angel nor simply demon.
Romance languages still display the older French range. Spanish genio, Italian genio, and Portuguese gênio can mean genius as well as a spirit. German Genie, borrowed from French, is almost only the talent word; for the Arabian being German prefers Dschinn. English divided the pair: genius for mind, genie for the lamp.
A collision, not a pedigree
A concrete marker is 1706, if one follows the Oxford first citation of the English Galland, or 1748 if one follows the date often given for the Arabic sense in running prose. Either number records a collision. The letters of genie come from Latin genius through French; the creature they now name comes from Arabic jinnī, chosen because it sounded close. The lamp is a narrative device, not an etymology. When English says the genie is out of the bottle, it is using that device, not the Roman birth-spirit and not the full Arabic taxonomy of the hidden ones.