(archaic) Towards the back or rear; backwards. / (archaic) In the rear; a distance behind. / By surprise; startled; dumbfounded. (see usage)

(obsolete) An abacus.

plural of aback

(British, US, dialectal) Behind; on the other side of

(figuratively) Surprised, shocked. / (nautical) Said of a ship, when the wind, suddenly changing, forces the sails aft against the mast.

past participle of take aback

Third-person singular simple present indicative form of set aback

(transitive) To startle or shock; to render (someone) confused or disconcerted.

present participle of set aback

(idiomatic, transitive) To surprise or shock; to discomfit. / (nautical, usually passive) Of a ship: to catch it with the sails aback suddenly.