Middle English word abutten comes from Old French a-, Old French bouter

Detailed word origin of abutten

Dictionary entry	Language	Definition
a-	Old French (fro)	(by extension) indicating a change of state. Indicating movement towards something. Intensifying prefix.
bouter	Old French (fro)	(reflexive, se bouter) to enter (into). To place; to put. To strike; to hit.
abuter	Old French (fro)
abutten	Middle English (enm)

Words with the same origin as abutten