>Never heard that oblok/oblak in Russian means "window" :)
>"Cloud" in Russian is "oblako" - the same as in Serbian, and "window" in Russian is "okno".
>:)

Then it was from some other language, probably kaykavian Croatian dialect :). I was 10 when I started learning, and I remember there was some such thing about windows. Ah, yes, "okno" means "framed opening", like the window frame or the entrance into a mine.

If you get into knowing more than one Slavic language, you get such pairs in dozens, and sometimes it's not the pairs themselves that get you confused, it's to which languages do they apply :).