unanimousness

Etymology tree
Proto-Indo-European *ís?
Proto-Indo-European *h₁óynos
Proto-Italic *oinos
Old Latin oinos
Latin ūnus
Latin ūni-
Proto-Indo-European *h₂enh₁-
Proto-Indo-European *-mos
Proto-Indo-European *h₂enh₁mos
Proto-Italic *anamos
Latin animus
Latin ūnanimusder.
English unanimous
Proto-Germanic *-in-
Proto-Indo-European *-h₂
Proto-Indo-European *-éh₂
Proto-Indo-European *-yéti
Proto-Indo-European *-eh₂yéti
Proto-Indo-European *-h₂ti
Proto-Germanic *-ōną
Proto-Germanic *-inōną
Proto-Indo-European *-dyé-
Proto-Germanic *-atjaną
Proto-Indo-European *-tus
Proto-Germanic *-þuz
Proto-Germanic *-assuz
Proto-Germanic *-inassuz
Proto-West Germanic *-nassī
Old English -nes
Middle English -nesse
English -ness
English unanimousness
From unanimous + -ness.