- although (conj.)
[although 词源字典]
- early 14c., althagh, compound of all + though, showing once-common emphatic use of all. "All though was originally more emphatic than though, but by 1400 it was practically only a variant of it, and all having thus lost its independent force, the phrase was written as one word" [OED].[although etymology, although origin, 英语词源]