unintentional, accidental
It was unintentional.
Un mouvement involontaire faillit lui échapper.
An involuntary movement almost escaped him.
It's unintentional.
Passepartout, la cause involontaire de ce retard, était désespéré.
Passepartout, the unwitting cause of this delay, was desperate.
Un jour ou l'autre, on retrouvera cet assassin involontaire.
Sooner or later, we'll find that accidental murderer.
— Monsieur Hire (1989)