genie

Is the word "genie" somehow related to Hebrew? Not exactly.

The word "genie" comes from the Latin genius, which in Roman mythology meant a "guardian spirit". From here the word developed to "spirit, incarnation, wit, talent" and much later came to mean "person of natural intelligence or talent".

But the French version of genius, genie, was used in the French translation of "Arabian nights" for jinni, the plural of jinn - "spirit" in Arabic. The Latin and Arabic words are not related, but in the past two hundred years the Arabic sense of the word genie has become dominant.

And where does jinn derive from?

Jinn (and majnun - "someone possessed by a spirit, crazy" also used in Israeli slang), comes from the Arabic root jn - meaning "to cover, conceal". This root is related to the Hebrew גנן - also meaning "to protect, shelter". From here we get magen מגן - shield, and hagana הגנה - defense (which according to Klein was coined by Rashi).

Surprisingly (to me at least), Klein and Kaddari do not connect גנן to gan גן - "garden". Jastrow, Steinberg and Stahl do make the connection. Jastrow defines gan as a "fenced-in place", and Stahl points out that the English words "guard" and "garden" are related as well. (However, neither the Online Etymology Dictionary (here and here) nor the American Heritage Dictionary (here and here) connect "guard" and "garden", so maybe this is just another coincidence.)