Does 'Niemcy' have cognates in other languages?
Nemec/Niemec/Nimec etc. (Niemcy is plural) are standad names for Germans in many Slavic languages. Literally, means "barbarian" or "speechless one" ("nemoj" is Russian for "unable to speak, mute") - clearly, Slavs had a certain view of the German language. Still, it has long lost its derogatory connotation, and is just the only word available. "Nemec" is the standard word for "German" (as an ethnic or national designation) in Russian, "Nimec" - in Ukrainian. Actually, "Germany" in Ukrainian will be "Nimetchina" (though still "Germania" in Russian).