astonishment · noun U /əˈstɑn.ɪʃ.mənt/Full view
astonishment
B2 very great surprise
Dictionary examples:

To my astonishment, she started laughing.

She gasped in astonishment.

Learner example:

To our astonishment, we were in front of a small house which seemed to have been built centuries ago. (First Certificate in English; B2; Greek)

Cambridge University Press