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

Encyclopedia: Aback

• chorioallantoic membrane
• chorioallantois
• choriomeningitis
• chorion
• chorionic
• chorionic villus
• chorionic villus biopsy
• chorionic villus sampling
• chorioretinitis
• Choriotis
• Choriotis australis
• chorister
• Chorizagrotis
• Chorizagrotis auxiliaris
• Chorizema
• chorizo
• chorography
• choroid
• choroid coat
• choroid plexus
• choroid vein
• choroidal artery
• choropleth map
• chortle
• chorus