underspend

The story

1. Proto-Indo-European*h₁én
2. Proto-Indo-European*h₁entér
3. Proto-Indo-European*h₂én
4. Proto-Indo-European*dʰeh₁-?
5. Proto-Indo-European*(H)n̥dʰí
6. Proto-Indo-European*(H)n̥dʰér
7. Proto-Germanic*under
8. Proto-West Germanic*undar
9. Old Englishunder-
10. Middle Englishunder-
11. Englishunder-
12. Proto-Indo-European*h₁éǵʰ
13. Proto-Indo-European*h₁éǵʰs
14. Proto-Italic*eks
15. Latinex
16. Latinex-
17. Proto-Indo-European*(s)pend-
18. Proto-Indo-European*(s)péndeti
19. Proto-Italic*pendō
20. Latinpendō
21. Latinexpendō
22. Proto-West Germanic*spendōn
23. Old Englishspendan
24. Middle Englishspenden
25. Englishspend
26. English todayunderspend

From under- + spend.