bonerific

The story

1. Proto-Indo-European*bʰeyh₂-
2. Proto-Germanic*bainaz
3. Proto-Germanic*bainą
4. Proto-West Germanic*bain
5. Old Englishbān
6. Middle Englishbon
7. Englishbone
8. Englishboner
9. Proto-Indo-European*tres-
10. Proto-Indo-European*troséyeti
11. Proto-Italic*troseō
12. Latinterreō
13. Proto-Indo-European*dʰeh₁-
14. Proto-Italic*θakos
15. Latinterrificus
16. Frenchterrifique
17. Englishterrific
18. English todaybonerific

Blend of boner + terrific.