The story
- Proto-Indo-European*h₂el-der.?
- Proto-Indo-European*h₂elnós
- Proto-Germanic*allaz
- Proto-West Germanic*all
- Old Englisheall
- Proto-Indo-European*to-
- Proto-Germanic*þau
- Proto-Germanic*þauh
- Proto-West Germanic*þauh
- Old Englishþēah
- Middle Englishalthagh
- English todayalthough
From Middle English althagh, from Old English compound of eall (“all (emphatic)”) + þēah (“though”). By surface analysis, al(l) + though.
Etymology from Wiktionary, CC BY-SA 4.0.