phosphite

Etymology tree
Proto-Indo-European *bʰeh₂-
Proto-Indo-European *bʰéh₂os
Proto-Hellenic *pʰáwos
Ancient Greek φᾰ́ος (phắos)
Ancient Greek φῶς (phôs)
Proto-Indo-European *bʰer-
Proto-Indo-European *bʰéreti
Proto-Hellenic *pʰérō
Ancient Greek φέρω (phérō)
Proto-Indo-European *-os
Proto-Hellenic *-os
Ancient Greek -ος (-os)
Ancient Greek -φόρος (-phóros)
Ancient Greek φωσφόρος (phōsphóros)bor.
Latin phōsphorusbor.
English phosphorus
Proto-Indo-European *h₃ed-
Proto-Indo-European *-os
Proto-Indo-European *h₃édosder.?
Proto-Italic *-ōtsos or *-otsos
Latin -ōsus
Old French -usbor.
Middle English -ous
English -ous
English phosphorous
Proto-Indo-European *-tósder.
Ancient Greek -της (-tēs)der.
Ancient Greek -ῑ́της (-ī́tēs)der.
Latin -ītēsbor.
French -iteder.
English -ite
English phosphite
From phosphorous + -ite.