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

• cardiac murmur
• cardiac muscle
• cardiac output
• cardiac pacemaker
• cardiac plexus
• cardiac resuscitation
• cardiac rhythm
• cardiac sphincter
• cardiac tamponade
• cardiac valve
• cardie
• Cardiff
• cardigan
• Cardigan Welsh corgi
• Cardiidae
• cardinal
• Cardinal Bellarmine
• cardinal compass point
• cardinal flower
• cardinal grosbeak
• Cardinal Newman
• cardinal number
• Cardinal Richelieu
• cardinal tetra
• cardinal vein