terrificness

Etymology tree
Proto-Indo-European *tres-
Proto-Indo-European *-yeti
Proto-Indo-European *-éyeti
Proto-Indo-European *troséyeti
Proto-Italic *trozeō
Latin terreō
Proto-Indo-European *dʰeh₁-der.
Proto-Italic *θakos
Proto-Italic *-fakos
Latin -ficus
Latin terrificusder.
French terrifiqueder.
English terrific
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 terrificness
From terrific + -ness.