boggler

[ bog-ler ]

noun

1. something, as an amazing fact, puzzle, or riddle, that astounds or defeats:

   The puzzle was a real boggler.

Word History and Origins

Origin of boggler¹

First recorded in 1600–10; boggle + -er ¹

Example Sentences

How they didn't manage to reverse it, though, is really the mind-boggler.

From The Daily Beast