The closest thing I can think of is "koniec tygodnia", but we use it mostly in phrases like "pod koniec tygodnia" (around the end of the week), which might refer to literal weekend, but also a few days back, or in some context end of the workweek (like around Thursday, Friday).
"Weekend" is in wide use and very precise.
Julian Tuwim in "Groch z kapustą" writes:
Foreign words should obviously be avoided when they can be replaced with Polish ones. But the creation of new words does not always give good results. We don't like the English "week-end" ("łykend" as the drunkards say ["łyk (np. piwa)"="a sip (e.g. of beer)"]) and we would be happy to replace it with a Polish equivalent but...
And then he lists the following proposals coming from a pre-war competition for the best Polish translation of the word "weekend":
Sobótka, wyraj, sobotnica, świątki, posobocie, świętówka, końcówka, potygodnie, wagary, dwudzionek, przedświątek, wypad, blak (?) [the question marks come from Tuwim], przedświęcie, tygodniak, dwudniówka, słońcówka, marzenko, radośnik, kojnik, pozdrówko, słońcorad, przedświętówka, błogodzień, świętowczas, przedświętówka, błogodzień, świętowczas, potrudzie, wyjaźdżka, kwiatkówka, świątecznik, wylotka, sobotowywczas, sobotniówka, wykapka, kresówka, trudokres, zamiastówka, półtoradniówka, czasopęd, miłoczas, sobniedziela, wydech, potygodniówka, hasanka, turniedziela, turświęto, soboniówka, niedzielanka, swobódka, kontyg (?), wywczaśnik, wytchniówka, niedziałek, sobotnia, wypoczka, odzipka, odnowa, półtorak, uzdrowystyk, krestyg, dobówka, popracówka, wagarówka, preczwilej, wigiliada, dobromarsz, przewietrze, wyrólaba, zefirówka, pokrzepka, odświeżka, półświątki, dowsiciąg, wczasik, saturniak, naturzanka, letkulig, anglosobótka, gajówka, siedmiodniówka, pokrzepiówka, wyskok, przyrodowypoczynek, radojzda, wyjrzywako, dobo świątek, krajówka, świętoczynek, dnioraj, sobotnik, niedzielnik, Świątnik, świątecznik, oponiak, ozonówka, przyśnięcie, przyświątka.
Most of the above words are really weird and Tuwim comments:
For word formation you need talent and inspiration. [...] But, as you can see, this blessed state has not accompanied the authors of these projects. Beware of "new monsters"! [Pol. "Strzeżmy się nowopotworów"!
A faux-Czech was sometimes used by Polish cabarets (I see it done less today) for humorous reasons. Generally the point is to make it sound somewhat like Czech while still being understandable to Poles (and not necessarily by actual Czechs).
There are many possible techniques for achieving that and different cabarets could do it slightly different. Overuse of diminutives, making up funny fake words, occasionally using real Czech words, using outdated synonyms, and various methods of Czechyfying Polish words, such as turning "G" into "H" or "Ł" into "L".
Polish Uncyclopedia even has an entire article about it written entirely in faux-Czech. http://nonsensopedia.wikia.com/wiki/Polski_j%C4%99zyk_czeski
I'll show it to my GF (native Polish), it will be beyond me for now lol. I do remember she gave me a funny (but inoffensive) name for Czechs that Poles use: "pepitka" or something (it was before I started studying Polish so I wasn't paying as much attention to spelling etc.)
Anyway I said it to a Czech girl I met in london and she had no idea what I was talking about :D
It's the nature of all languages to "borrow" words- especially when they are describing an object or idea from that other language. English is full of them but if you are a native speaker and learned it as a child you may not realize that certain words come from another language. The concept of "weekend" is fairly new to Polish workers who worked a six day week for many years. I am a workshop facilitator and when I did workshops in Poland I found it difficult to translate some of my "technical" terms - so I just said it in English and the group began to use these words- for example "sharing" and "feedback" -
There are at least two kinds of loanwords. One, where „weekend” belongs, contains words that expresses not yet named concepts (for which we would need to create new word). Others, like commonly seen in business, are created, because the loanwords are easier to use for certain people or they just didn't know that the equivalent already existed. Those have the drawback of being harder to understand for people unfamiliar with the jargon.
"overwhelmed" is a little off though. It's a very natural process in any language, aside from a weird few artificially curated languages like Icelandic. It's normal for languages to evolve and mingle like this.
I mean, it's cool that languages like Icelandic are so heavily moderated that they are essentially an active museum exhibit, but it's not normal for a language to be preserved like that. As society evolves, so does language to fit the needs of the speakers.
Fin de semaine can be used for more than just the weekend. For instance, when setting up a meeting "en fin de semaine", you would obviously not be referring to the weekend, but to the second half of the work week, so Thursday or Friday. Week-end (normally spelled with the "-") is very commonly used in French. So often in fact, that you will find it in the dictionary.
Bien sûr que fin de semaine a bien des sens suivant les circonstances, il en va de même pour tout autre langage que je connaisse, et son utilisation repose donc sur le contexte. Dans le cas qui nous importe, ce dernier est facile à déterminer, et tu le dis d'ailleurs toi-même à travers ton exemple, entre travail/scolarité (se mettre d'accord sur un rendez-vous avec son employeur/ses collègues, ou rendre un devoir), donc Jeudi ou Vendredi, et loisirs/détente, le Samedi ou Dimanche, il n'y a pas d'ambiguité. Ce n'est pas parce qu'il figure dans un dictionnaire, qu'il acquiert forcément une légitimité, même cas de figure pour des mots tels que "parking" (au lieu de stationnement), "blacklister" (mettre en indésirable), "burn-out" (surmenage) et bien d'autres, ils sont ce qu'ils sont, à savoir des anglicismes. Pire que tout, cela montre juste à l'interlocuteur une ignorance, une méconnaissance, une irrévérence crasse à sa langue maternelle. La langue française, tout comme beaucoup d'autres, est suffisamment riche pour pallier à ce genre de problèmes, et si le mot "week-end" n'a pas d'équivalent ""précis"", c'est simplement parce qu'elle n'en a pas besoin comme je l'ai indiqué plus haut. Si l'on veut être précis, on indique le jour, point barre.
Of course "fin de semaine" has many meanings considering the circonstances, same goes with any other language that i know of, and so its use relies solely on context. In this case, the context is easy to spot, and you said yourself so through your example, between work/education (fixing a meeting with your employer/colleagues or submit homework = Thursday or Friday), and leisure time (hobbies or meeting with family/friends = Saturday or Sunday), there is no ambiguity whatsoever. Just because a dictionary features this word, doesn't mean it has any legitimacy, same goes with words like parking instead of "stationnement", to blacklist instead of "mettre en indésirable", burn-out instead of "surmenage" and so on so forth, they are what they are : anglicisms. Worst of all, it just shows how bad you are with your mother tongue, unable to find the right word at the right moment, and thus relying on foreign words to compensate, what a disgrace. French language, just like many others, is rich enough to find any equivalence, and if the word "week-end" has no ""precise"" equivalent, it's simply because it doesn't need one, as stated above. If you want to be precise, then you indicate the day, end of the line.
Well, that's how it is. We use „w” basically for everything that is longer than a day (from weekends to the entire millenias). Of course it doesn't apply for relative terms, like English "in two weeks" (za dwa tygodnie) or "a month ago" (miesiąc temu). Also used before days of the week, like "on Friday" (w piątek).
„Do” is always +gen. „Po” is usually +loc, but can be occasionally +acc. And „w” can be +loc or +acc, but the ratio is closer to the middle than with „po”.
And explaining it with translations to English can be tricky, since the prepositions don't match exactly (but you've probably already noticed that). It's probably best to learn by examples, but if you really want, there are between 5 to 10 usage explanations per either one of these words. If you really want, you might search them on Polish Wiktionary for definitions and examples.
Just to prevent confusion. "Days free from work" are called "выходные" alright, but the word "выходной/выходные" (sg/pl) in this particular sense is an adjective literally meaning "[smth] for going out". You can have a "выходное платье" - a dress "for going out", i.e. for special occasions, or "выходные туфли" - a best pair of shoes for going out.
So "выходной день" is a day off, literally "a day for going out." ("День" is omitted in informal speech, "выходной" being used as a substantivised adjective.) The plural form "выходные" usually means weekend, as Saturday and Sunday are the usual days off, but "выходной" can also refer to any day off you might have on any day of the week, and "выходные" can also refer to a group of non-working days around some special day like New Year, which is not necessarily a weekend.
So yes, any weekend is выходные[*], but not every выходные would be a weekend.
[*] Even if you work weekends and have your days off on weekdays, you can also refer to weekend as "выходные" in the calendar sense, in situations when your work/rest is irrelevant. If work/rest is relevant, you'll somehow make clear which выходной you mean, the weekend or the day off.