The story
- Proto-Indo-European*dʰeyǵʰ-
- Proto-Indo-European*dʰinéǵʰti
- Proto-Italic*θingō
- Proto-Italic*fingō
- Latinfingō
- Latinfictus
- Latinfictīcius
- Englishfictitious
- English todayfictitiousness
From fictitious + -ness.
Etymology from Wiktionary, CC BY-SA 4.0.