genocider

Etymology tree
Proto-Indo-European *ǵenh₁-
Proto-Indo-European *-os
Proto-Indo-European *ǵénh₁os
Proto-Hellenic *génos
Ancient Greek γένος (génos)
Proto-Indo-European *kh₂eyd-der.
Proto-Italic *kaidō
Latin caedō
Proto-Indo-European *-h₂
Proto-Indo-European *-eh₂
Proto-Italic *-ā
Latin -a
Latin -cīda
Proto-Indo-European *-yós
Proto-Italic *-ios
Old Latin -ios
Latin -ius
Latin -ium
Latin -cīdiumder.
Middle French -cidebor.
English -cide
English genocide
Proto-Indo-European *-yósder.
Proto-Italic *-āzijos
Latin -āriusnom.
Latin -āriusbor.
Proto-Germanic *-ārijaz
Proto-West Germanic *-ārī
Old English -ere
Middle English -ere
English -er
English genocider
From genocide + -er. Piecewise doublet of genocidaire.