The story
- Proto-Indo-European*h₁es-
- Proto-Germanic*sunjō
- Proto-West Germanic*sunnju
- Old Englishsynn
- Proto-Indo-European*lewh₁-
- Proto-Indo-European*lewHs-
- Proto-Germanic*leusaną
- Proto-Germanic*lausaz
- Old Englishsynlēas
- Middle Englishsynneles
- English todaysinless
From Middle English synneles, senneles, from Old English synlēas (“without sin; sinless”), equivalent to sin + -less. Compare Dutch zondeloos (“sinless”), German Low German sündelos, sündlos (“sinless”), German sündenlos (“sinless”), Icelandic syndlaus (“sinless”).
Etymology from Wiktionary, CC BY-SA 4.0.