take aback, to

take aback

Surprise, shock, as in He was taken aback by her caustic remark. 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. Its figurative use was first recorded in 1829.
See also: aback, take

take aback, to

To surprise or discomfit. This term originally was nautical, describing sails that press against the mast and therefore suddenly impede a vessel’s progress. It was used figuratively from the early nineteenth century on. Dickens used it in his American Notes (1842): “I don’t think I was ever so taken aback in all my life.” It is heard less often today but has not died out.
See also: take