take sb aback

take sb aback (surprise greatly; knock someone's socks off) — застать врасплох

Example 1: We were taken aback by the news. — Новость захватила нас врасплох.

Example 2: I was taken aback by her audacity.

Example 3: He was taken aback by her caustic remark.

See also
[catch sb off guard]
[catch sb with one's pants down]
[catch sb in the act]
[catch sb unawares]
[застать врасплох]

This idiom comes from nautical terminology of the mid-1700s, when be taken aback referred to the stalling of a ship caused by a wind shift that made the sails lay back against the masts.