"He is not my friend, he is my acquaintance."

Translation: On nie jest moim przyjacielem, on jest moim znajomym.

[PolvandenBleek]

On nie jest moim przyjacielem, a moim znajomym?

[Jellei]

Makes sense, added.

[JoyceThomp6]

Why can't one say On to nie przyjaciol, etc. It's the same thing?

[janezg]

Can you also say: "To nie mój przyjaciol, to mój znajomy"?

[Jellei]

Yes. Technically the grammar is different ([This/That/It] is not...), but "He is not..." is a natural translation. And the Polish sentence sounds pretty natural. So I guess I can add it.

One note: - you have a small typo, it's "przyjaciEl" :)

[Avt08]

Please add

[Jellei]

I did. 5 months ago.

[JorisH.]

What about 'kumpel' as 'friend'? Or is that too much in the area of slang?

[Szparag]

It is a slang word so you definitely shouldn't use it in formal situations. ;) But it's pretty popular especially among young people.
It would be a good equivalent of "kolega/przyjaciel".

[Chicagoski]

this negation takes narzędnik instead of dopełniacz?

[Jellei]

Okay, it seems that today a lot of people have problems with negations ;) Well, it's a very common misconception.

The rule is NOT "negation = dopełniacz (Genitive)".

The rule is "negated Accusative = Genitive".

Every other case, when negated, stays the same anyway. As Accusative is very widely used, people see that a lot and start thinking that every negation takes Genitive. But it does not.

[Chicagoski]

That helps a lot. Dziękuję :)

[AlisonSinc]

This isn't clear to me. Why is a genitive not required, and why do we go to an instrumental?

[Ten_Pies_I_Brew]

When "jest" connects two nouns, or a pronoun to a noun, it always takes the instrumental on one side or the other. The only exception is when the subject is "to".

[kumpakri]

Why not "On nie jest moim kolegą, on jest moim znajomym"? It doesn't say "he is my best friend".

[Jellei]

Well, "best friend" is "najlepszy przyjaciel", so here "najlepszym przyjacielem".

On one hand, you are right. But... your sentence just seems surprising. "kolega" on its own is pretty vague, it may be someone not really important for you, just some guy you know. It just seems strange to make him even less important by saying "znajomy". Just seems not worth saying.

Still... we can't say that it's just wrong. I guess it won't hurt to accept it.

[kumpakri]

I see your point. Thanks.

[TrevorChri14]

This type of question is not real, it is more like a test in grammar. Fine if you enjoy grammar, but where can we practice it for any who needs practice to build recall? I have no use for it here in Poland, and i would not on the internet. Od czasu do czasu, yes, so the grammar stays. This, no.

[Arnoldpitt]

Why does przyacielem end- em and znajonym end -ym?

[alik1989]

Znajomy is technically an adjective which functions as a noun in this sentence. So it has an adjective declension pattern.