Real versus nominal definitions in the language of 19th century German legal dissertations Definition is included in the basic (scientific) activities (methods). The results of the definition are communicated in the language. In my paper I take up the topic of functions performed by definitions in the development of knowledge about law. The basis for my deliberations are selected fragments of German scientific treatises from the 19th century. I am particularly interested in the above topic in the context of the principle of dividing definitions into real and nominal definitions adopted since the times of Aristotle. In my paper I try to establish the status of definitions used in the texts I analyse. The fundamental research problem is whether the definitions formulated by the 19th century German law theorists are certificated, real, classical essential definitions – established in the final analysis (this would be consistent with the expectations of some researchers of the language of law related to its character, i.e. its accuracy, accuracy), or whether these definitions are understood in a fallible way, subject to revision and change, which are the results of the field of law.