I have noticed that the Russian word пока means the same as zatím in Czech in both meanings. The first is as a conjunction and the second use means goodbye. I am aware that in Czech the equivalent expression to пока as a conjunction is "zatím co" but I still think this is a very interesting coincidence.
Example of the first use:
- он смотрел телевизор пока она спала
- on se díval na televizi, zatím co ona spala
The second use is a word meaning goodbye.
I also know that Russian has за тем which
has the same meaning as Czech zatím but cannot be used as a greeting. (EDIT: This is incorrect, see @Yellow Sky's answer)
So, the question is, how did it come so, that these seemingly unrelated words have the same two uses. I tried looking up both of them in Wiktionary with no success but this is where my etymology skills end.