Definition from Wiktionary, the free dictionary
- (figuratively) Surprised, shocked.
1963, Margery Allingham, chapter 8, The China Governess:
- It was a casual sneer, obviously one of a long line. There was hatred behind it, but of a quiet, chronic type, nothing new or unduly virulent, and he was taken aback by the flicker of amazed incredulity that passed over the younger man's ravaged face.
- (nautical) Said of a ship, when the wind, suddenly changing, forces the sails aft against the mast.