RB cats
Grisette: because she was grey (blue)
Minouche: (daughter of Grisette) because she shoudl have a French name too, minouche is a female cat
Meo: daughter of Grisette -I was told at that time it was the Vietnamese word for cat -nbo idea whether it is true

Now:
Filou: His official name in his papers was Solo, because he was a single child. I found that sounded to sad and too dark and, anticipating that he would be a mischievous charming boy I called him Filou which means just that

Tigris: he was called Blacky by the people where he was born but this sounded to me like a dog's name; he looks at the first glance like the classical Tiger but as he is also of noble descent (even if it's mixed ) I called him Tigris which sounded more exclusive. You can also pronounce it French, then it means "little grey one" I had no idea that the river Tigris would be discussed that much these days