- Archaic backward; back
- Naut. backward against the mast, as the sails of a square-rigged vessel in a wind from straight ahead
Origin of abackOld English on bæc, at or on the back
- Naut. in an unmanageable condition, as because of a sudden shift of wind to the opposite side of the sails
- startled and confused
- By surprise: He was taken aback by her caustic remarks.
- Nautical In such a way that the wind pushes against the forward side of a sail or sails.
- Archaic Back; backward.
- (archaic) Towards the back or rear; backwards. [First attested prior to 1150.]
- (archaic) In the rear; a distance behind. [First attested prior to 1150.]
- By surprise; startled; dumbfounded.
- (nautical) Backward against the mast; said of the sails when pressed by the wind from the "wrong" (forward) side, or of a ship when its sails are set that way. [First attested in the late 17th century.]
- By setting the foresail aback and the headsail in the middle one can bring a fore-and-aft rigged sailing boat practically to a halt even in heavy wind.
- (by surprise): Preceded by a form of the word take.
- (obsolete) An abacus.