noun or participle which takes 'suru'
astonish; amaze; surprise greatly
A direct loanword used as a suru-verb, often in casual or emphatic contexts. Less common than native alternatives like 驚かせる, but used for a dramatic, modern feel.
彼のパフォーマンスは観客をアストニッシュさせた。
His performance astonished the audience.
そのニュースには本当にアストニッシュしたよ
I was really astonished by that news.