The word "Jellicle" first appears in "Old Possum's Book of Practical Cats" by T. S. Elliot, specifically the poem "The Song of the Jellicles". The name "Jellicle cat" is derived from an attempt by T.S. Eliot's infant niece to say "dear little cat"
Jellicle Cats come out to-night
Jellicle Cats come one come all:
The Jellicle Moon is shining bright -
Jellicles come to the Jellicle Ball.
by Zanti September 15, 2006
to leap or climb upon an object, surface, or person in an overly dramatic cat-like manner
We were about to leave, but then Evan had to go and jellicle cat on the car. We had to wait for him to get off the hood before we could go.
by merwenna November 25, 2012
An incredibly annoying gender-confused feline.

Used in a sentence:

Because Jellicles are and Jellicles do
Jellicles do and Jellicles would
Jellicles would and Jellicles can
Jellicles can and Jellicles do

as you can see, a jellicle cat is a terrible, terrible thing.
Interviewer: Is there a societal metaphor here?
Andrew Lloyd Webber: Dude, it's a play. About cats. Jellicle Cats
One’s vote for something deserving of a reboot, reset, restart, reimagining, return, or revival; from “Cats,” wherein, it’s used to describe a vote cast for one who (apparently) gets a second chance at life, ((possibly) via reincarnation.)
Many games are deserving of reboots, but my Jellicle Choice is Silent Hill.
by Gill M. June 8, 2019