Four letter word for "complete"

I don't normally do crossword puzzles. I hate asking for help on them but I did do one yesterday and I felt smart.

If you are stuck on this Sunday's Fox Trot here are the answers. That's right, I didn't think any of you needed them.

Across:

1. Koi
4. WA
6. Gump
8. In
9. St
10. Ugly
12. Feral
14. Zits
15. It
17. OT
18. Eons
20. OS
21. PGE

Down:

1. Kgs
2. Outfits
3. IM
4. Willing
5. Any
7. Purse
11. GA
13. ET
14. Zoo
16. Tse
19. Op