Definitionen
1.NounA bizarre world, where everyday rules do not apply.
2.NounA way into such a world."These mushrooms will take you down the rabbit hole, man."
3.NounA time-consuming tangent or detour, often one from which it is difficult to extricate oneself."I'm also a fan of a really obscure book series, but that's a rabbit hole that we won't get into.; While writing my paper, my research went down several rabbit holes that were only marginally related and wasted a lot of my time."
4.NounThe initial clue that leads to an alternate reality game.
5.NounUsed other than figuratively or idiomatically: see rabbit, hole. The entrance to a rabbit warren or burrow; the whole warren or burrow.