aback aback /əˈbæk/

adverb

1. By surprise  ( aback )
   by surprise
    Taken aback by the caustic remarks
   taken aback by the caustic remarks
   
2. Having the wind against the forward side of the sails  ( aback )
   having the wind against the forward side of the sails
    The ship came up into the wind with all yards aback
   the ship came up into the wind with all yards aback