Jinni - The Arab singular (whence the French "genie"); fem. Jinniyah; the Div and Rakshah of old Guebre-land and the "Rakshasa,' or "Yaksha," of Hinduism. It would be interesting to trace the evident connection, by no means "accidental," of "Jinn" with the "Genius" who came to the Romans through the Asiatic Etruscans, and whose name I cannot derive from "Gignomai" or "genitus." He was unknown to the Greeks, who had the Daimon, a family which separated, like the Jinn and the Genius, into two categories, the good (Agatho-daemons) and the bad (Kako-daemons). We know nothing concerning the Jinn amongst the pre-Moslemitic or pagan Arabs: the Moslems made him a supernatural anthropoid being, created of subtle fire (Koran chapts, xv. 27; lv. 14), not of earth like man, propagating his kind, ruled by mighty kings, the last being Jan bin Jan, missionarised by Prophets and subject to death and Judgement. From the same root are "Junun" = madness (i.e., possession or obsession by the Jinn) and "Majnun" = a madman. According to R. Jeremiah bin Eliazar in Psalm xli. 5, Adam was excommunicated for one hundred and thirty years during which he begat children in his own image (Gen. v. 3) and these were Mazikeen or Shedeem - Jinns.
Elsewhere in his translation, Burton notes that Jann is usually taken as the plural form of Jinni.
Classes of Jinni include the Ifrit ("pronounced Aye-frit", fem. Ifritah) and the Marid (fem. Maridah) who are usually, but not always, hostile to mankind.
You can look for more on the Jinn in tales of the Thousand Nights and a Night and in the Koran.