"Moral decay" is a term used to describe the decline or fall of the moral values of a civilization. This concept, which is sometimes called decadence, is most often illustrated by the decline of the Roman Empire due to malaise and loss of civic virtue.
Merriam-Webster defines decadence as "behavior that shows low morals and a great love of pleasure, money, fame, etc." This can be seen in individuals and societies as a pattern of abandoning previously held beliefs and values. Several scholars blame decadent behaviors and corrupt morals for the decline of the Roman Empire, but this is by no means an established fact.
Moral decay is a relative concept, as it is predicated on a set of morals that may be different depending on the society in question. As of 2014, there are some who feel that the current state of affairs in the world is indicative of moral decay. This is debatable, since there is no way to directly measure the effect that specific moral codes have on the world as a whole and how changes in those moral codes affect society on a global level. Morality and moral decay are subjects that are discussed in several fields of study, such as anthropology and sociology.