A den is a small room in a house where people can pursue activities in private. [1] In North America, the type of rooms described by the term den varies considerably by region. It is used to describe many different kinds of bonus rooms, including family rooms, libraries, home cinemas, spare bedrooms, studies or retreats., DEN definition: 1. the home of particular types of wild animal 2. a room in a house or apartment, used for…. Learn more., Define den. den synonyms, den pronunciation, den translation, English dictionary definition of den. n. 1. The shelter or retreat of a wild animal; a lair. 2. A cave or hollow used as a refuge or hiding place. 3. A hidden or squalid dwelling place: a den of, Den is an Old English word meaning “shelter for a wild animal.” While we still use it in this sense, the word has taken on some additional meanings. For example, den can refer to a room that's used primarily for relaxing, watching television, and socializing with friends., DEN meaning: 1 : the home of some kinds of wild animals; 2 : an informal and comfortable room in a house, Definition of den noun in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more..