ˌopen-ˈmouthed BrE AmE adjective , adverb
with your mouth wide open, because you are very surprised or shocked:
We stared open-mouthed as the plane came down.
ˌopen-ˈmouthed BrE AmE adjective , adverb
with your mouth wide open, because you are very surprised or shocked:
We stared open-mouthed as the plane came down.
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012