Feudalize is a word used to describe the process of creating or adopting a feudal system, characterized by a hierarchal social structure and a system of reciprocal obligations between lords and vassals. Some synonyms for feudalize include fiefdom, feudalizing, vassalage, and serfdom. Other related terms include feudalism, feudal system, and feudal lord. These words are often used interchangeably, but they all refer to the same societal structure that was common in medieval Europe. While the term feudalism is often criticized for being too general and oversimplifying the complexity of medieval societies, it remains a useful term in discussions about political and economic systems of the Middle Ages.