I am familiar with the word "fulano" (name given to an unnamed person, sort of like the English "John Doe") through Portuguese. I am aware of its use in Spanish as well. But I was quite surprised to hear my Persian instructor, in giving an example of the present perfect tense, say "Folaan nesheshteh ast". I asked her about it, and she mentioned that she thought it was originally a Turkish word. It doesn't help that my instructor is originally Palestinian, but lived in Iran for most of her life. So her first language is Arabic, and she does get somewhat mixed up at times.
After some googling, I found a few sites, most of which claim the origin of the word is Arabic (and possibly originally Egyptian). This would make sense, as it could easily have spread to Persian and Turkish by way of Arabic, and to Spanish and ultimately Portuguese as well. But I found one rather heated thread in which one user adamantly insists the word must be of Greek origin. To be fair, it does not sound particularly like an Arabic root to me. Another user insists that the "aan" ending (alef+nuun; sorry, no Arabic font at work) is a typical Persian grammatical ending, so the word must be Persian. I'm not convinced by this, but who knows?
Any insight? I find it curious that a word that seems so unusual to me (as a native English speaker) seems to be so international and widespread!