Where does “bycause” come from?

bycause (English) comes from English by, from Middle English by, from Old English bī, from Proto-West Germanic bī, from Proto-Germanic bi, from Proto-Indo-European h₂m̥bʰi, from Proto-Indo-European h₂n̥tbʰi, from Proto-Indo-European h₂énts — on, onto.

Ancestry of “bycause”, step by step

bycause traces back through two separate lines of ancestry.

via English by

StepLanguageWordMeaning
1EnglishbyNear or next to; From one side of something to...
2Middle Englishbybe
3Old Englishlullaby!; near, by; by, near, around
4Proto-West Germanicby, at; near, around
5Proto-Germanicbiby, at; near, around
6Proto-Indo-Europeanh₂m̥bʰiaround, on either side of, about; in exchange...
7Proto-Indo-Europeanh₂n̥tbʰi
8Proto-Indo-Europeanh₂éntsforehead; front
9Proto-Indo-Europeanh₂ent-face; forehead; front
10Proto-Indo-Europeanh₂en-on, onto

via English cause

StepLanguageWordMeaning
1EnglishcauseThe source of, or reason for, an event or action;...
2Middle Englishcausecause
3Old Frenchcausecause
4Latincausacause, reason; case, claim, contention; motive,...
5Old Latincaussacause, reason, purpose; case, claim; Archaic form...
6Proto-Indo-Europeankawd-teh₂
Every word from Proto-Indo-European h₂en-