I have recently been devoting time to a conlang that I hope to use — among other things — to write a journal in. In the last couple of days, I have been thinking about how to describe different rooms in a home. While I still have not finalized all of the words I will need in this language, I thought it might be useful to write a blog post detailing the most common strategies for naming rooms.
Please note that I have not done anything like a full literature review, or even much googling beyond simply perusing Wiktionary. There are probably a lot of options from less widely spoken languages that I have not seen. This is good enough for my purposes, and will probably be useful if you are looking for ideas for your own language, but it is likely not enough for some projects. Please do feel free to comment on things you think I have missed!
Terms for 'kitchen' tend to be straightforward references to cooking or a clear metaphorical stand-in for cooking (e.g. fire or a stove).
The terms common in Indo-European language are almost always in the first category, and the vast majority of them ultimately derive from the Latin noun coquus 'cook': English kitchen is in this category, as is German Küche, French cuisine, Spanish cocina, Russian кухня, etc. Many other languages follow a similar pattern with a different root, i.e. Finnish keittiö from keittää 'to boil, cook', Greenlandic igaffik from igavoq 'to cook, prepare food', or Arabic مَطْبَخ /matˤ.bax/ from طَبَخَ /tˤa.ba.xa/ 'to cook'.
For the most part, terms that buck this trend are still based on clear metaphorical references to cooking, e.g. Basque sukalde (literally 'fire zone') or Malay dapur (which also means 'stove'), or to the qualities of prepared food.
Thus, while a global survey would surely reveal fascinating exceptions, at the most general level there is one obvious way to say kitchen.
Many languages refer to the living room with a term either equivalent to the English living room (German Wohnzimmer, Estonian elutupa, etc.) or something closely related: Finnish olohuone 'being room' and similar terms in other languages, sitting room in English and equivalent terms in other languages, Bulgarian дневна /ˈdnɛvnɐ/ 'day room' and similar terms, etc. The common theme is that the living room is the room where you do most of your daytime activities and/or sit around and just exist. Words like lounge in English also evoke this idea.
In other languages, you get a term that can also refer to (or once referred to) a hut or other small dwelling, e.g. Ingrian pertti or Icelandic stofa (which is ironically related to stove in English). This makes sense given how human dwellings have evolved over time as technological and social advances have raised the average person's standard of living — when your home has only one room, that is where you do your living, and then as you begin to have the resources to add more rooms, you start adding them for specific things that you want to move out of the main room.
Another common option is some take on "guest room" or "meeting room": Russian гостиная, Vvietnamese phòng khách, etc. In English, the word parlour ultimately evokes this image as well, implying that the room is for talking.
And finally, you have salon and similar terms which literally mean "big room". This likely needs no explanation — in most houses, the living room is the largest room, intended to be the primary living space and social center of the dwelling. Even though the etymologies of these terms often go back further than present-day architecture and living standards, the concept remains straightforward.
There is surprisingly little variation here. Most languages use "bed room" or "sleeping room" (possibly using a term that metaphorically evokes sleeping, e.g. Finnish makuuhuone 'lying down room'); the only common alternative seems to be a term that just means room, or possibly a small, private room).
This is born out in English as well: my room typically refers to the speaker's bedroom, and would be somewhat less typical in reference to e.g. one's office, even in one sleeps in a shared bedroom and has a private office tucked away somewhere in the house.
First off, since it might come in handy: in Europe, lightly phonologically adapted versions of toilet and WC are nearly universally understood, even if those terms are not what you would see on a construction blueprint or hear in a private home. But that is not what we are truly here to talk about.
Here, it is important to distinguish between a toilet in the European sense — a very small room used solely for excreting and disposing of waste and washing your hands afterwards — and a bathroom — a room where you might take a shower or bath, which may or may not also contain a toilet (the plumbing fixture) but has many other functions as well. American squeemishness has led to the latter term taking over both functions in American English, to the point where technical terms like "half bath" are needed to unambiguously describe the former concept.
There is basically only one way to say bathroom in the European sense: some form of "bath room" or "washing room", or another term derived via a slightly different strategy that still unambiguously relates to bathing or washing.
Words for toilet, on the other hand, cover a much wider swath of ground, due to the numerous euphemisms that people invvent to describe something that nobody wants to talk or think about any more than they have to. In addition to various forms of toilet, water closet, and (like in American English) bathroom or washroom, you also get terms like "little house" (evoking an outhouse), "little room", "place for necessities", "men's/women's room" (due to the common practice of gender-segregating toilets), etc. And that is before diving into slang, nautical terms like head, terms that are actually rude, etc. This is a place where a conlanger should feel free to get creative — a naturalistic language is almost guaranteed to have widely-used, culturally appropriate euphemisms for toilets.
Foyers, atria, garages, and other rooms are beyond the scope of this post, especially given that I started writing it after thinking about how to name spaces in my two-room apartment. They are not, however, beyond the scope of the question — your conlang may have (or need) a way to express them, and I encourage you to share it!