because

The story

1. Proto-Indo-European*h₁ep-
2. Proto-Indo-European*h₁éps
3. Proto-Indo-European*h₁épi
4. Proto-Indo-European*h₁pi
5. Proto-Germanic*bi
6. Proto-West Germanic*bī
7. Old Englishbī
8. Middle Englishby
9. Proto-Italic*kaussā
10. Old Latincaussa
11. Latincausa
12. Old Frenchcause
13. Middle Englishcause
14. Middle Englishbi cause
15. English todaybecause

From Middle English bi cause, from bi (“by”) + cause, modelled on Old French par cause.

First known use, by meaning

• 15th–17th c. So that, in order that.
• from 20th c. or before On account of, because of.