[The difficulties involved in arriving at a comprehensive definition of the phenomenon pain.].

Although pain is part of our everyday life, to date there has been no generally accepted definition of pain. In this article is presented on a survey the various attempts to define pain. Four types of definitions can be distinguished: (a) definitions of pain oriented to a stimulus; (b) definitions of pain oriented to a reaction; (c) definitions of pain oriented to the experience of pain; (d) definitions of pain by determining the components of pain. The advantages and disadvantages of these types of definition are discussed. Using a component model, it is demonstrated that scientific investigation of pain can only grasp single aspects. Therefore, the nature of the subject implies that interdisciplinary cooperation is necessary.