gobsmacked
adjective /ˈɡɒbsmækt/
/ˈɡɑːbsmækt/
(British English, informal)- so surprised that you do not know what to say
- I was gobsmacked when she told me the news.
Word Origin1980s: from gob ‘mouth’ + smack ‘slap’, with reference to being shocked by a blow to the mouth, or to clapping a hand to one's mouth in astonishment.