口くちあんぐり

noun

dumbfounded; open-mouthed

Describes a state of being so surprised or shocked that one's mouth hangs open. Often used adverbially with と or as a noun with する.

• その知しらせを聞きいて、彼かれは口くちあんぐりと立たち尽つくした。

  Upon hearing the news, he stood there dumbfounded with his mouth open.

• あまりの光こう景けいに、みんな口くちあんぐりしていた。

  Everyone was open-mouthed at the incredible sight.