At the individual level it's called, "getting married". Victims of marriage stop bar hopping (nomadic) in favor of boring nights at home turning into a mental vegetable (agricultural). Marriage is a form of slow death practiced by all civilizations.
It would be called "settling" or "urbanization" but the last only in the case of major sites (towns).
This happens when Hunter/Gatherers settle down and start to work the soil. This can also be called an agricultural society.
