What is the meaning of the word "rabbit hole"?

Rabbit hole" is a metaphor for a situation or state that transports someone into a surreal state, either troubling or wonderful.

Definitions:

A complicated or difficult situation, especially one that is difficult to get out of. NOUN
- Their advice is not meant to send you down a rabbit hole, and involve you in chaos and disorder.
A hole in the ground dug by a rabbit. NOUN
- He broke his ankle when his foot got caught in a rabbit hole.
A situation in which you become so interested in a subject or an activity that you cannot stop trying to find out about it or doing it. NOUN
- You can kind of find yourself getting sucked into various attention rabbit holes.