1. Civility: This is the most common noun form of "civil," referring to politeness and courtesy.
Example: "The debate was conducted with surprising civility."
2. Civilian: This noun refers to a person not in the military or police forces.
Example: "The soldiers were ordered to protect the civilians."
3. Civilization: This noun refers to a state of human society marked by the development of social institutions, art, science, and technology.
Example: "The ancient Egyptians created a sophisticated civilization."
So, the best noun form for "civil" depends on the specific meaning you want to convey.