expression, noun-modifying (irregular)
jaw-dropping; shocking; surprising
Idiomatic expression describing something so surprising or shocking that one's mouth stays open in astonishment. Often used prenominally to modify a noun.
See also: 開いた口も塞がらぬ
His sudden resignation was jaw-dropping news.
その光景を見て、あいた口が塞がらぬ思いだった。
Seeing that sight, I was utterly shocked.
A more general term for being stunned or dumbfounded, not limited to the jaw-dropping imagery.
Standard kanji spelling for this idiomatic expression.
Mixed kanji-kana spelling; 開いた is sometimes written in kana for simplicity.
Literally 'the opened mouth does not close', a set phrase expressing astonishment. The exact origin is uncertain, but it is a natural metaphorical extension of the physical reaction to shock.