Meaning of “boggle” - Learner’s Dictionary

boggle

verb uk us /ˈbɒɡl/
the mind boggles (also US it boggles the mind) INFORMAL

something you say if something is difficult for you to accept, imagine, or understand:

The mind boggles at the stupidity of some people.
→ See also mind-boggling

(Definition of “boggle” from the Cambridge Learner’s Dictionary © Cambridge University Press)