From Wiktionary, the free dictionary
From kitten + -ness.
kittenness (uncountable)
- The quality of being a kitten.
2015 October 9, Marjorie Ingall, “‘Leo: A Ghost Story,’ ‘Max the Brave’ and More”, in New York Times[1]:Max is an expressive huge-eyed black ball of kinetic kittenness who pops against each page’s bright, differently colored background.