radioarsenic

The story

1. Latinradius
2. Englishradio-
3. Proto-Indo-European*ǵʰelh₃-
4. Proto-Indo-European*ǵʰl̥h₃enyom
5. Proto-Indo-Iranian*ȷ́ʰr̥Hanyam
6. Proto-Iranian*jr̥Hanyam
7. Old Median*zaranyam
8. Old Median*kā
9. Old Median*zaraniyakā
10. Middle Persian*zarnīk
11. Classical Syriacܙܪܢܝܟܐ (zarnīḵā)
12. Arabicالزَرْنِيخ (az-zarnīḵ)
13. Medieval Greekἀρσενικόν (arsenikón)
14. Latinarsenicum
15. Middle Frencharsenic
16. Middle Englisharsenik
17. Englisharsenic
18. English todayradioarsenic

From radio- + arsenic.