French word assaillant comes from Latin salire ((jump, spring). (salt, sprinkle).), Old French saillir, Latin ad- (To.)

Detailed word origin of assaillant

Dictionary entry	Language	Definition
salire	Latin (lat)	(jump, spring). (salt, sprinkle).
saillir	Old French (fro)
ad-	Latin (lat)	To.
a-	Old French (fro)	(by extension) indicating a change of state. Indicating movement towards something. Intensifying prefix.
assilio	Latin (lat)	(intransitive) I spring or leap (to or upon); rush (at).. (intransitive, of water) I dash (against).
asaillir	Old French (fro)	(transitive) to jump on.
assaillir	French (fra)	To assail; to assault; to attack.
assaillant	French (fra)	Assailant Assailant. Assailling.

Words with the same origin as assaillant