Indeed.

Yeah. One of my friends had ten languages listed on her Facebook last I saw. Now, there's no question that she's brilliant in languages, and she's a Fleming who grew up in Luxembourg, making her quadrilingual or quintilingual almost per definition, and most of the other six are Slavic languages that are all related to each other, but even so it seems like a bit of a stretch if your criterium for "knowing" a language is to speak it fluently and understand/read it without effort.

Heh. I think that's something Americans are more inclined to do - since Americans often take only one foreign language in high school, and sometimes that one language is Latin, so it makes sense for them to list it somehow, to show they did learn something in their one foreign language class. Or at least that's the impression I get.

I'm inclined to say the most crucial criterium would be basic conversational fluency. Which is why I hesitate to state that I "know" Arabic, even after all the effort I've put into it, and despite the fact that I know certain words or grammatical things about standard/Classic Arabic that even many Arabs wouldn't know.

But of course it depends on the context. If the context of the conversation is clearly about being able to read, you might claim to know a language even though you can barely speak it.

Apparently I'm the only one here who does this, judging by the answers, but it's quite common here... on my resume, I distinguish between the different aspects of knowing a language when listing my language abilities. For instance, I can read books and texts in German, and with some more effort in Portuguese and even Italian, which might be useful to my employer for some purposes, even when my conversational German is dubious and my conversational Portuguese non-existent. Of course, for jobs that have nothing to do with Italian or Portuguese, I won't bother listing that. If I listen every language I "know" to any degree on my CV, it starts to look absurd, particularly when half of them are followed by qualifiers. So I list the ones I speak at a decent level, and those of the rest that might be relevant to the job in question.

That entirely depends on how much it's about bragging.

There are four languages that I feel I can say I "know", without too many qualifiers. From best to worst: Dutch, English, French, Spanish. Then if you go into the more dubious cases, German, which I read nearly as easily as I do French thanks to its similarity to Dutch, but can't write or speak too well, and Arabic, which is a complicated case. And then the ones that I'd only list in very specific circumstances: Portuguese, Italian, Turkish, Finnish, and the dead languages Latin, Ancient Greek and Ancient Hebrew (with the dead languages I suppose my criterium is being able to read a text given a good dictionary, a grammar for occasional consultation and huge amounts of time - i.e., knowing the alphabet, the most important grammar and some amount of vocabulary).