Nomos is a word from ancient Greek which means both law and custom. I've been asked what I use it to denote. We use this, as in eco-NOM-ics and astro-NOM-y. Which is why internet trolls should learn etymology.
To understand human behavior one must start from the doctrine of incorporation: mental activities are carried out by a physical body. While the locus of that activity is the nerves of the brain, it is not limited to those nerves.
Morality, as we understand it, stems from a few sections of the brain that parse what is normally done, and applying that to the inner decision making. The inner patter is morality, however the outer patterns are the fractal result of these inner patterns. The clash between the intent of morality - to fit in - and the results, which often lead to anger, insult, and tragedy, have occupied writers, and dramatists, for centuries.
What the human mind has not evolved, is a sense of how to understand the bigger picture in the same direct way. We learn language and morality because that is the way our brains generally grow. We learn literature and ethics, only by a higher order processing and projection into other than simple step by step understanding.
Every society grows out of the morals of its members, but the connection between the morals that people learn and the ethics that it creates is in direct.
A nomos is the connection between desired ethical results and the morals that make them up, a sphere of connected individuals who learn what is moral by observing each other, and forming a stable attractor.