To maim something is to disfigure it through force or violence. Wartime battles have a tendency to maim soldiers.
The verb maim is related to mayhem, which, historically, was the act of hurting another person so badly that they couldn’t defend themselves. To maim a person or animal, even if it’s an accident, is to render them defenseless or disfigured, and it frequently includes the loss of a limb. The goal of driving defensively is to avoid an accident that could maim you, your passengers, or other people on the road.