What does Jellicle mean in Cats?

Could you please elaborate on the meaning of the term "Jellicle" as it's used in the context of the musical "Cats"? I'm curious to understand the significance it holds within the story and how it contributes to the overall narrative. Is it a reference to a specific breed of feline, or does it carry a deeper, symbolic meaning? I'd appreciate it if you could provide some insight into this intriguing aspect of the show.