untomboyish

The story

1. Proto-Indo-European*né
2. Proto-Indo-European*n̥-
3. Proto-Germanic*un-
4. Proto-West Germanic*un-
5. Old Englishun-
6. Middle Englishun-
7. Englishun-
8. Aramaicתאמא
9. Aramaicתאומא (təʾōmā)
10. Ancient GreekΘωμᾶς (Thōmâs)
11. LatinThōmās
12. Middle EnglishThomas
13. Middle EnglishThomme
14. EnglishTom
15. Englishtom
16. Proto-Indo-European*bʰā-
17. Proto-Germanic*bō-
18. Proto-West Germanic*bōjō
19. Old English*bōia
20. Middle Englishboye
21. Englishboy
22. Englishtomboy
23. Englishtomboyish
24. English todayuntomboyish

From un- + tomboyish.