Prefixes – em, en, fore, post, and over
1. forewarning
2. postscript
3. postwar
4. encourage
5. overweight
6. overflow
7. foresight
8. embellish
9. emblazon
10. engrave
11. endanger
12. foreground
13. embitter
14. overdue
15. foreknowledge
16. overprotect
17. embankment
18. embattle
19. enlistment
20. enlighten