1. An abacus.


  1. Towards the back or rear; backwards.
  2. In the rear; a distance behind. <ref name=SOED/>
  3. By surprise; startled; dumbfounded.
  4. 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. <ref name=SOED/>
    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.

The above text is a snippet from Wiktionary: aback
and as such is available under the Creative Commons Attribution/Share-Alike License.

Need help with a clue?
Try your search in the crossword dictionary!