Progress in psychiatry depends on accurate definitions of disorders. As long as there are no known biologic markers available that are highly specific for a particular psychiatric disorder, clinical practice as well as scientific research is forced to appeal to clinical symptoms. Currently, the nosology of obsessive-compulsive disorder is being reconsidered in view of the publication of DSM-V. Since our diagnostic entities are often simplifications of the complicated clinical profile of patients, definitions of psychiatric disorders are imprecise and always indeterminate. This urges researchers and clinicians to constantly think and rethink well-established definitions that in psychiatry are at risk of being fossilised. In this paper, we offer an alternative view to the current definition of obsessive-compulsive disorder from a phenomenological perspective. TRANSLATION: This article is translated from Dutch, originally published in [Handbook Obsessive-compulsive disorders, Damiaan Denys, Femke de Geus (Eds.), (2007). De Tijdstroom uitgeverij BV, Utrecht. ISBN13: 9789058980878.].