the world > action or operation > safety > protection or defence > vigilance > vigilant or on one's guard [phrase] > in provision against the case that (2)
in (also for, on, upon) adventure: in case, for fear. Cf. anaunter, adv. anauntrins, conj. enaunter, conj. Obsolete.
In provision against the event that, so as to provide for the possibility that; lest it happen that.