monophosphate

The story

1. Proto-Indo-European*men-
2. Proto-Hellenic*mónwos
3. Ancient Greekμόνος (mónos)
4. Ancient Greekμονο- (mono-)
5. Englishmono-
6. Proto-Indo-European*bʰeh₂-
7. Proto-Indo-European*bʰéh₂os
8. Proto-Hellenic*pʰáwos
9. Ancient Greekφᾰ́ος (phắos)
10. Ancient Greekφῶς (phôs)
11. Proto-Indo-European*bʰer-
12. Proto-Indo-European*bʰéreti
13. Proto-Hellenic*pʰérō
14. Ancient Greekφέρω (phérō)
15. Ancient Greekφωσφόρος (phōsphóros)
16. Latinphōsphorus
17. Frenchphosphore
18. Frenchphosphate
19. Englishphosphate
20. English todaymonophosphate

From mono- + phosphate.