Standing between a thing and what would harm it. Protection is a posture held before the harm arrives, or it is only regret.
Latin protegere (to cover in front, to shield): pro- (in front) + tegere (to cover); a protective posture is the covering held ready before harm arrives, not applied after.
Standing between a thing and what would harm it, before the harm rather than after. Held too late, the same posture is only regret wearing the name of protection.