manganous

Etymology tree
Pre-Greekbor.?
Ancient Greek Μάγνης (Mágnēs)
Proto-Indo-European *-h₂
Proto-Indo-European *-éh₂
Proto-Indo-European *-i-eh₂
Proto-Hellenic *-íā
Ancient Greek -ῐ́ᾱ (-ĭ́ā)
Ancient Greek Μᾰγνησῐ́ᾱ (Măgnēsĭ́ā)der.
Medieval Latin Magnēsia
Medieval Latin -ius
Medieval Latin magnēsius
Medieval Latin magnēsiader.
Italian manganeseder.
French manganèsebor.
English manganese
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 manganous
From manganese + -ous.