Answer: boggling

AnswerCrossword Clue
boggling(of a person) Hesitate or be anxious at
bogglingBOGGLE, to hesitate (to hold back or delay)
bogglingCause (a person or a person's mind) to be astonished in such a way
boggling(of a person or a person's mind) Be astonished or overwhelmed when trying to imagine something