@Phil, I don't know. Immortality could work well in other parts of the world, but everyone who has read "Monday Begins on Saturday" knows that in Russia an immortal person probably wouldn't have been able to live through the tsarist period without getting de-nostriled and exiled to Solovetz in perpetuity. And I think the internet connection in Solovetz is still not good enough for itаlki which is changing the way the world learns foreign languages.
@drasvi, well, I'm pretty sure I didn't use it in my childhood, and I've never heard it from a child in my whole life (at least, not as a synonym of кошка). I mean, everyone knows what the word means but it was something only really old people used when talking to children. You can't be 90 years old now, can you? And I heard "котенька" in Moscow, by the way. Are you sure you're not behind the times?