Background: The term 'mental retardation' (MR) is outdated and has changed to 'intellectual disability' (ID). Unfortunately, this decision did not follow a nosology approach. The aim of this overview is twofold: (1) to provide a conceptual background and framing on the ID/MR field to other psychiatrists, and (2) to provide a nosology-based perspective to the debate on the name and concept of MR/ID. Method: This conceptual paper is based on a literature review and on an iterative process of debate within the WPA Section 'Psychiatry of Mental Retardation'. Results: ID may be regarded not as a disease or as a disability but as a syndrome grouping (metasyndrome) similar to the construct of dementia. It includes a heterogeneous group of clinical conditions, ranging from genetic to nutritional, infectious, metabolic or neurotoxic conditions. The ID metasyndrome is characterized by a deficit in cognitive functioning prior to the acquisition of skills through learning. The intensity of the deficit is such to interfere in a significant way with individual normal functioning as expressed in limitations in activities and restriction in participation (disabilities). Conclusions: The name 'developmental cognitive impairment' is here suggested to coexist with ID for naming the metasyndrome previously called MR following a polysemic-polynomious approach.