"Matěj, you are a good friend."

Translation: Matěji, vy jste dobrý přítel.

[alexxxius83]

Is it OK to use "přítel[kyně]" when talking about merely friends? I heard it means more like a boyfriend/girlfriend and simply friends are called "kamarád[ka]" or "kamoš".

[endless_sleeper]

It is ok, but you might get some strange looks. :) If you want to avoid that, use kamarád/kamarádka. Kámoš/kámoška is more like 'buddy.'

[sanquii]

It is OK in this case. The word "přítel[kyně]" implies a closer and more trustful relationship than "kamarád[ka]". The sentence sounds very earnest, like something you would say after your friend would offer you help in a difficult time.

When speaking about boyfriends and girlfriends, possessive pronouns are usually present ("můj přítel", "moje přítelkyně").

[zariuq]

Is the "vy" there because Matěj is an older friend?

[sanquii]

Since the sentence says they're friends, they probably use "vy" mutually. So I would interpret it as a professional relationship.

[sebytro]

Why is it Matěji and not Matěj?

[JanLyko]

We adress Matěj, so it's vocative
https://en.wiktionary.org/wiki/Mat%C4%9Bj#Declension