fictitiousness

Etymology tree
Proto-Indo-European *dʰeyǵʰ-
Proto-Indo-European *dʰi-né-ǵʰ-ti
Proto-Italic *θingō
Proto-Italic *fingōder.
Latin fingō
Latin fictus
Proto-Indo-European *-ikos
Proto-Italic *-ikos
Latin -īcus
Proto-Indo-European *-yós
Proto-Italic *-ios
Old Latin -ios
Latin -ius
Latin -īcius
Latin fictīciusbor.
English fictitious
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 fictitiousness
From fictitious + -ness.