Dictionary.com
Thesaurus.com
Synonyms

aback

American  
[uh-bak] / əˈbæk /

adverb

  1. toward the back.

  2. Nautical. so that the wind presses against the forward side of the sail or sails.


adjective

Nautical.
  1. (of a sail) positioned so that the wind presses against the forward side.

  2. (of a yard) positioned so that its sail is laid aback.

idioms

  1. taken aback, surprised and disconcerted.

    I was taken aback by his harsh criticism.

aback British  
/ əˈbæk /

adverb

    1. startled or disconcerted

    2. nautical (of a vessel or sail) having the wind against the forward side so as to prevent forward motion

  1. rare towards the back; backwards

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

aback More Idioms  
  1. see take aback.


Etymology

Origin of aback

First recorded before 1000; Middle English abak, Old English on bæc “to the rear”; a- 1, on, back 1