That's the verb 'kitten'. I don't have the newest edition of van Dale either, but, as a native, I can assure you that we use 'kitten' for a baby cat (plural: 'kittens').
(I don't know if you like WikiWoordenboek (Wikitionary), but they say that the noun 'kitten' is a new born cat.)
I looked it up on the Van Dale website and it didn't come up as a "baby cat" either (and I made sure to check both the Nederlands-Nederlands and the Nederlands-Engels section). Perhaps it's more of a dialect thing? I mean, as it doesn't come up in an official dictionary... I don't really like Wikitionary because of the fact that it's made by regular users, so I do not regard it as a trustworthy source. I mean, I'm a History teacher, and the things kids get from Wikipedia are plainly outrageous. Every time I read an assignment done using Wikipedia as a source I can tell, because most times it's plagued with inaccuracies and biased interpretations. Therefore, I do not really trust Wikipedia nor Wikitionary.