Internet Startup or Word a So-Called Friend Played That Made It Obvious They've Been Cheating at Words With Friends?

1. ETAERIO

2. HOUWSER

3. SWYTCH

4. QUIBI

5. MUZJIKS

6. QUIZZIFY

7. SYZYGY

8. QUARTZY

9. ZOOTAXY

10. BOOSTR

11. WEELTH

12. OBLOQUY

13. ZONULAR

14. FROUZY

15. CLOZE

16. NUDZH

17. ZYMES

18. PLOTZ

19. BYRL

20. ZLOTY

21. RYND

22. WYCH

23. AIRILY

24. ISOBATH

Internet Startup: 2, 3, 4, 10, 11
Word played by a now-former friend: 1, 5, 7, 9, 12, 13, 14, 16, 17, 18, 19, 20, 21, 22, 23, 24
Both: 6, 8, 15