radargram

The story

1. Englishradiotelegraphyclip.
2. Englishradio
3. Latindētēctiō
4. Englishdetection
5. Proto-Indo-European*h₂ent-
6. Proto-Indo-European*h₂énts
7. Proto-Indo-European*h₂énti
8. Proto-Germanic*andi
9. Old Englishand
10. Middle Englishand
11. Englishand
12. Proto-Indo-European*(H)rek-
13. Proto-Celtic*reketi
14. Gaulish*rekosbor.?
15. Proto-Indo-European*h₃reǵ-
16. Proto-Germanic*rinkaną
17. Proto-Germanic*rankaz
18. Frankish*rankbor.?
19. Vulgar Latin*rencus
20. Old Frenchreng
21. Old Frenchrengier
22. Middle Englishrengen
23. Englishrange
24. Englishranging
25. EnglishRADAR
26. Englishradar
27. Ancient Greekγράμμα (grámma)
28. English todayradargram

From radar + -gram.