Core

A female cat's Regina, typically used for mating with a male cat's member (penis).

*IF YOU READ WARRIOR CATS BY ERIN HUNTER:
Whitestorm: Hey Brindleface! Wanna do some mating?
Brindleface: Yeah sure! My core is all ready for you!

Whitestorm: Awesome! I'll be licking you inside out until you cum inside of me!
Brindleface: My core is dripping with cooling juices specially for you! Our kits will be the best in the forest, baby!