Aback

Aback \A*back"\ ([.a]*b[a^]k"), adv. [Pref. a- + back; AS. on
   b[ae]c at, on, or toward the back. See Back.]
   1. Toward the back or rear; backward. "Therewith aback she
      started." --Chaucer.
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   2. Behind; in the rear. --Knolles.
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   3. (Naut.) Backward against the mast; -- said of the sails
      when pressed by the wind. --Totten.
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   To be taken aback.
      (a) To be driven backward against the mast; -- said of the
          sails, also of the ship when the sails are thus
          driven.
      (b) To be suddenly checked, baffled, or discomfited.
          --Dickens.
          [1913 Webster]See also:
Back To be taken aback 

Aback \Ab"ack\ ([a^]b"ak), n.
   An abacus. [Obs.] --B. Jonson.
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