This study aimed to define the term 'profound and multiple learning disabilities' (PMLD). A shared understanding of terminology or diagnostic terms describing groups of individuals is important for the purposes of strategic development, service planning, and the provision and equity of service delivery. A literature review provided different definitions and meanings associated with the term. The meaning attributed to the definitions was explored in focus groups and individual interviews (face to face and telephone) with service managers, commissioners, practitioners, frontline healthcare staff and family carers who provide services, support and care for people with PMLD. Further iterative discussions were held with a smaller group over the precise wording of the chosen definition to ensure there was a shared and common understanding. Personal characteristics for the purpose of this study are defined as diagnoses, disabilities, impairments, activity restrictions and other characteristics which represent a person with PMLD.