Green’s Dictionary of Slang

1. a pint or half-pint pot [i.e. a small cat n.⁴ ].

1861

(con. 1840s–50s) H. Mayhew London Labour and London Poor I 414/1: At this lodging-house cats and kittens are melted down, sometimes twenty a day. A quart pot is a cat, and pints and half pints are kittens.

2. (US Und.) the junior member of a gang, used to check places susceptible to a robbery, etc. [dimin. of SE cat, but note cat n.¹ (3a)].

1908

Denton (MD) Journal 11 July 1/8: The ‘kitten’ is a boy, young man, or cripple, whose duty it is to visit houses and places of business, apparently begging food or selling shoestrings [...] and who then reports to the gang the ‘lay of the land.’.

3. a young woman [dimin. of SE cat but also play on cat n.¹ (1c)].

4. the vagina [var. on cat n.¹ (2a)].

1995		L. Stavsky et al. A2Z 49/1: hittin’ the kitten – v. engaging in sexual intercourse.
2001		‘Lara the Webmistress’ 🌐 21 Mar. In the back of the cab, he wrapped his hand around the inside of my thigh and worked it up to my bare kitten. He stroked at my button and he laughed out loud when he could feel how wet I was.
2016		Kash Doll ‘Summer Sixteen’ 🎵 Nigga stop bitching I just let you eat up the kitten.