Definition of back nine in English:

back nine

noun

Golf
  • The final nine holes on an eighteen-hole course.

    ‘he had a double bogey and a triple bogey on the back nine’
    • ‘But the world No.1's game became uncharacteristically creaky over the back nine.’
    • ‘DiMarco moved into contention with birdies on the first six holes on the back nine.’
    • ‘Harrington went on to complete the back nine in 35.’
    • ‘He was under no pressure al the way through the back nine.’
    • ‘I played so much better than Sally in the back nine that she actually offered to propose me as a member.’