It's a diminutive cat. (As in, "the problem with kittens is they grow into cats" :-) ).
It should not accept "kitten"; kitty or ❤❤❤❤❤ only. A kitten is a kismacska.
In the US that word also has a vulgar meaning, so be careful how and with whom you use it. We are much more likely to say "kitty" as a diminutive.
In British English too - but possibly less offensive than in the US. Standard gag in a family friendly show would be an elderly lady asking if anyone had seen her ❤❤❤❤❤. That said I've surveyed several of my friends. All all their cat "❤❤❤❤❤" or "puss" . None use "kitty". Incidentally, "❤❤❤❤❤" is the older word.
Right - hence the elderly woman using the term innocently. :)
Then again, we US-English speakers have a word that refers to the buttocks and is pretty inoffensive here, but is very offensive in the UK and maybe other English-speaking countries. Nothing to do with cats, though.
Just noticed stupid DL has changed the normal UK English term of affection for ones cat to a censored line of hearts. (Whereas I suspect it'll let me type "fanny" which is rude in UK English)