boggle verb definition in Surprise topic from the Oxford Advanced Learner's Dictionary

boggle

 verb: Surprise topic
[intransitive] boggle (at something) (informal) to be slow to do or accept something because you are surprised or shocked by it Even I boggle at the idea of spending so much money.(informal) if something boggles the mind or the mind boggles at it, it is so unusual that people find it hard to imagine or accept The vastness of space really boggles the mind. ‘He says he's married to his cats!’ ‘The mind boggles!’