concenter/kənʹsentə/ verb trans and intrans

• backspace
• backspin
• backstabbing
• backstage
• backstairs
• backstay
• backstitch
• backstop
• back story
• backstreet
• backstroke
• backswing
• back to/at square one
• back to back
• back-to-back
• back to front
• back to the drawing board
• backtrack
• back up
• backup
• backveld
• backward
• backwardation
• backwards
• backwards and forwards