To gasp (in surprise, awe, fear, etc.); to have one’s breath taken away.
初めて見たその景色に思わず息を呑んだ。
I involuntarily gasped at the scenery I saw for the first time.
演奏の最後で観客は息を呑んだ。
The audience gasped at the end of the performance.
その知らせを聞いて彼は一瞬息を呑んだ。
He gasped for a moment when he heard the news.
事故の現場はあまりに悲惨で、通行人は皆息を呑んだ。
The accident scene was so tragic that passersby were all aghast.