Abstract Purpose: To provide a contemporary definition and comprehensive classification of dry eye disease. Methods: A literature search and a consensus process involving members of the Definition and Classification subcommittee and the DEWS membership. Results: A new definition of dry eye was developed, reflecting the current understanding of dry eye disease. The committee recommended a three part classification comprising i. Aetiology ‐ accommodating the multiple causes of dry eye, ii. Mechanism, indicating how the several causes of dry eye may act through a common pathway, and, iii. Severity, offering a rational basis for therapy in an individual case. In the course of discussions certain principles were established, such that ocular surface health is maintained by a functional unit whose integrity is essential for surface homeostasis. Interruption of the regulatory feedback loops, for instance by reducing the sensory drive to lacrimal secretion, is a potential risk factor for dry eye. Further, it was stressed, that any form of dry eye may interact with and exacerbate any other forms of dry eye, as part of a vicious circle, and that, in time, a change in tissue reactivity may be established leading to a disease which is self‐perpetuating in the absence of its original trigger. Conclusions: The guidelines presented are not intended to override the clinical assessment and judgment of an expert clinician but should prove helpful in the conduct of in clinical practice and research.