What connects these words?

1234567891011121314151617181920
Across
  1. 1. one over par for a golf hole
  2. 3. one under par for a golf hole
  3. 8. a tool with a shorter with a head that features a large, flat, angled face
  4. 10. a free swaying motion
  5. 12. from start to finish in one go
  6. 14. golf ball support
  7. 15. a piece of turf cut out of the ground by a golf club
  8. 16. a numerical measure to help competition
  9. 19. often the final tool
Down
  1. 2. the location of the golf hole
  2. 4. an area of the grass that is deliberately kept longer
  3. 5. last hole in golf
  4. 6. a hole that is crooked or bend like the hind leg of a dog
  5. 7. a warning to get out of the way
  6. 9. a ground on which a specific sport is played
  7. 11. a tool used to project an object a long distance
  8. 13. part of a golf course
  9. 17. golfers tool of the trade
  10. 18. even score
  11. 20. score better than a birdie