Stone Soup, Prefixes

1. untied
2. repay
3. disagree
4. preheat 
5. unafraid
6. return
7. preschool
8. dislike
9. disappear
10. resell
11. precook
12. prepay
13. unbeaten
14. reprint
15. unwrap
16. tiger
17. planet
18. spider
19. unlucky
20. recover