The story
- Proto-Germanic · inherited from*þurnīnaz“of thorns”
- Proto-West Germanic · inherited from*þurnīn
- Old English · inherited fromþyrnen“thorny, of thorns”
- Middle English · inherited fromthornen
- English todaythornen
From Middle English thornen, from Old English þyrnen (“thorny, of thorns”), from Proto-West Germanic *þurnīn, from Proto-Germanic *þurnīnaz (“of thorns”), equivalent to thorn + -en.
Etymology from Wiktionary, CC BY-SA 4.0.