Where does “abovesigned” come from?

abovesigned (English) comes from English above, from Middle English aboven, from Old English ābufan, from Old English bufan, from Proto-West Germanic *biobanā, from Proto-West Germanic *obanā, from Proto-Germanic ubanē, from Proto-Germanic upp.

Ancestry of “abovesigned”, step by step

abovesigned traces back through two separate lines of ancestry.

via English above

StepLanguageWordMeaning
1EnglishabovePhysically over; on top of; worn on top of, said...
2Middle Englishabovenabove
3Old Englishābufanabove
4Old Englishbufanabove
5Proto-West Germanic*biobanā
6Proto-West Germanic*obanāfrom above
7Proto-Germanicubanēfrom above
8Proto-Germanicuppup, upwards
9Proto-Germanicubunder
10Proto-Indo-Europeanupóunder, below
11Proto-Indo-Europeanh₃ewp-

via English signed

StepLanguageWordMeaning
1EnglishsignedHaving a signature; endorsed; Having both...
Every word from Proto-Indo-European h₃ewp-