The story
- Proto-Indo-European*de
- Proto-Indo-European*déh₁
- Proto-Italic*dē
- Latindē
- Latinde-
- Proto-Indo-European*dʰeh₁-
- Proto-Indo-European*dʰeh₁k-
- Proto-Indo-European*dʰh₁kyéti
- Proto-Italic*θakjō
- Proto-Italic*fakjō
- Latinfacio
- Latindēficiō
- Latindēfectus
- Englishdefect
- Proto-Indo-European*lewh₁-
- Proto-Indo-European*lewHs-
- Proto-Germanic*leusaną
- Proto-Germanic*lausaz
- Englishdefectless
- English todaydefectlessness
From defectless + -ness.
Etymology from Wiktionary, CC BY-SA 4.0.