Favorite words in a foreign language that don't exist in your native language

[kanewai]

Like Deinonysus, it's usually grammatical features that I miss in English. I really like inclusive and exclusive we, as well as "dual" pronouns.

I also like the 'reported past' in Turkish. It's the past tense, but for things you have only heard about but can't vouch for personally.

For specific words, Micronesian had the best obscenities. They usually involved scents, genitalia, and your closest relative. They were so amazingly vile, but also really common.

[Mista]

Fr chez. Ger bei. Cz u. Sw hos. Icel hjá.
I can remember a time I thought this was a special thing French did. Now I know it isn't ... it's a bit like the moment you find out your parents aren't perfect.

And the neatest thing of all is that French chez comes from Latin casa and Swedish hos comes from hus - they both mean "house", etymologically speaking, and are a lot more similar to the English than you would think

[Neurotip]

Fr chez. Ger bei. Cz u. Sw hos. Icel hjá.
I can remember a time I thought this was a special thing French did. Now I know it isn't ... it's a bit like the moment you find out your parents aren't perfect.

And the neatest thing of all is that French chez comes from Latin casa and Swedish hos comes from hus - they both mean "house", etymologically speaking, and are a lot more similar to the English than you would think

Awesome! So obvious once you know, but it never occurred to me. It still gives me a weird feeling of vertigo when nouns turn into prepositions (though I guess it's easier when the noun could be inflected for case).
Now you mention it, Magnússon's Orðsifjabók tells me that hjá is "þgf. eða stf. af *hīwa- 'heimilisfólk'", i.e. dative or locative [?] of *hīwa- 'household' (yes, I had to look that up ) and is related to hjón '(married) couple'.

PS Now what language do we think he's referring to with the asterisk? Not Old Norse, and IIUC you wouldn't give an unadorned *h in a PIE reconstruction. Does he mean Proto-Germanic maybe? Blimey, looks like he does, or something similar: search 'hiwa' in this page. Isn't Google wonderful!

[Chung]

Fr chez. Ger bei. Cz u. Sw hos. Icel hjá.
I can remember a time I thought this was a special thing French did. Now I know it isn't ... it's a bit like the moment you find out your parents aren't perfect.

Indeed.

To add to this, there are the postpositions juures and luona in Estonian and Finnish respectively while Hungarian and Turkish rely on the suffixes -nál/-nél and -da/-de respectively to pull off a translation of chez etc. in reference to static location. English looks like the oddball by relying often on the adverbial phrase "at [x]'s place" (although I do also consider it grammatical to say "at [x]'s" (i.e. omit "place")).

On a related note, there are fewer "untranslateable" concepts out there than it appears even when restricted to comparisons restricted to one language with the native one. The reality is that if some humans have already seen or experienced something/someone, odds are that they've found a way to express it whether it be with a phrase, borrowing, calque or lexicalization. My target languages aren't that special no matter how personally appealing they are.

"Untranslateability" or just absence of lexcialization for anything across languages is more likely to happen with phenomena that are heavily associated with a particular speech community's culture/environment as seen in jargon (e.g. "strikeout", "howzat" or "safety" in sports, Italian terms in classical music) or kinship (e.g. Korean kinship terms).

[Sizen]

These aren't necessarily my favourite words, but some of them are very specific and don't have concise equivalents in English as best as I can tell.

Japanese

わらしべ長者する (warashibechouja suru) - to make a series of ever-better trades starting with something of little value and ending with something of great value. This one comes from a folktale: Straw Millionaire.

晴れ男 (hareotoko) and 雨男 (ameotoko) - a man who causes it to be sunny (hare) or rainy (ame). You can also replace 男 (otoko) with 女 (onna) for a woman.

腹上死 (fukujoushi) - death during sex. If you break down the characters, it's stomach - above - death.

団欒する (danran suru) - gathering together with close family/friends and having a good time while chatting (often sitting in a circle, like around a table).

Ainu

ニプシフム (Unfortunately I don't know the proper spelling in Katakana or Romaji. My guess would be ニㇷ゚シフㇺ or Nipsihum, but I can't find it.) - The sound of trees splitting caused by liquids in the trees freezing due to a quick drop in temperature.

French

science infuse - knowing things without having learned them; innate knowledge. This technically exists in English, I just don't think it exists in quite the same way as a set phrase.

bifler - to slap someone with one's... *ahem*... man parts. Portmanteau of "bite" and "gifler".

[nooj]

Fr chez. Ger bei. Cz u. Sw hos. Icel hjá.
I can remember a time I thought this was a special thing French did. Now I know it isn't ... it's a bit like the moment you find out your parents aren't perfect.

Some Spanish dialects have this as well, you'll see variations of anca, ca etc.

[Ogrim]

I really like the Spanish word sobremesa - the idea of spending time relaxing and chatting with your family or friends after a meal.

If I can give an example of a word in my native language which (as far as I know) does not really exist in other languages it would be utepils (outdoor beer). After a long cold winter there is something very appealing about being able to sit outside on a terrace sipping a cold beer.

[StringerBell]

In Polish there is the word "rozmówca" which I believe means a person taking part in a conversation. I know that technically in English we have the words "interlocutor" and "conversationalist" but in reality almost no one ever uses these words to refer to a person involved in a conversation so they seem out of place. (Though doesn't sound weird at all to say that someone is "a great conversationalist".)

Unless I'm completely overlooking something obvious, there isn't a great word to refer to a person who is taking part in a conversation. I guess we sometimes call someone a "conversation partner" but that's not really the same thing, plus it sounds really awkward unless you are referring to a specific situation like a conversation partner who is helping you to improve your conversational skills in another language, not someone with whom you are having some chit chat while standing in line at the supermarket.

I think in English we just don't really have a title or a name for this person. We'd say instead, "I had/am having a conversation with..."

[cjareck]

In Polish there is the word "rozmówca" which I believe means a person taking part in a conversation. I know that technically in English we have the words "interlocutor" and "conversationalist" but in reality almost no one ever uses these words to refer to a person involved in a conversation so they seem out of place. (Though doesn't sound weird at all to say that someone is "a great conversationalist".)

We have also "dyskutant" as someone who takes part in a discussion or a debate. There also is a sophisticated word "interlokutor" but is seldom used and most people would not understand what does it mean.

My favourite Russian word (I will think about Hebrew and Arabic one later) is автоматчик which means infantryman with a submachine gun. In Russian - Polish military dictionary I found a translation to "Fizylier" (Fusilier), but that is also a name for line infantry from Napoleonic Wars.

[tarvos]

斬捨御免, Kirisute gomen "authorization to cut and leave the victim's body"

It used to be a thing that samurai could strike someone if someone from a lower class besmirched their honor.

It is nowadays used in Japanese as a way of saying "I apologize in advance for what I'm going to do"