Emile Durkheim used the term “anomie” to refer to a situation when the rules of society are breaking down or have broken down. When this happens, people feel uncomfortable. They feel that they do not know what they are supposed to do or how they are supposed to act. This can lead (as in a famous study by Durkheim) to people committing suicide because they feel rootless.
Durkheim felt that anomie was a problem that would arise more often in modern societies than in older and less complex societies. In more traditional societies, people live more homogeneous lives. They all do the same sorts of jobs and live the same sorts of lives. Tradition is strong and so people know how they are supposed to act. In our more modern society, these conditions do not exist. Our societies are complex and diverse. We live among people who have different values than we do. The rules that govern our society are not nearly as clear as they once were. Therefore, we can come to feel anomie. We no longer know what the rules of society are because our society is no longer as cohesive as it once was.