The story
- Proto-Indo-European*dem-
- Proto-Indo-European*dṓmder.?
- Proto-Italic*domVnos
- Latindominus
- Latindominicus
- Vulgar Latin*dominicella
- Vulgar Latin*domnicella
- Old Frenchdomnizelle
- Old Frenchdamoisele
- Middle Englishdameisele
- Englishdamsel
- Proto-Indo-European*plew-
- Proto-Indo-European*plewk-
- Proto-Indo-European*pléwketi
- Proto-Germanic*fleuganądeverb.
- Proto-Germanic*fleugǭ
- Proto-West Germanic*fleugā
- Old Englishflēoge
- Middle Englishflye
- Englishfly
- English todaydamselfly
From damsel + fly, where damsel ultimately from Vulgar Latin *domnicella (whence also French demoiselle, Portuguese donzelinha). Compare Danish vandnymfe, Dutch juffer, Swedish jungfruslända, Welsh mursen. Also compare ladybird, ladybug, nymph.
Etymology from Wiktionary, CC BY-SA 4.0.