Jinn
Wikipedia says this about the origin of the word: "Jinn is an Arabic collective noun deriving from the Semitic root JNN (Arabic: جَنّ / جُنّ, jann), whose primary meaning is 'to hide' or 'to adapt'". It goes on to say that some relate the term to the Roman "genius," coming from the PIE root *g̑enh₁-, "give birth, produce".
Interestingly, the same page gives another Arabic word from the JNN root: janīn (جَنِين, 'embryo').