Educationally subnormal was a term used historically in the United Kingdom to refer to children with very limited intellectual abilities. Throughout much of the 20th century, British education policy focused on separating these children from the wider school population and they were often viewed as being incapable of meaningful improvement. Children placed in this category were disproportionately boys, from less wealthy households and immigrant families.
The term "mentally defective" was used in the early 20th century to refer to children and adults with intellectual disabilities. Beginning in the 1910s, children deemed to be in this category began to be formally classified as such and were taken into the custody of the state if their home environment was believed to be unsuitable. Separate schools were also established for "mentally defective" children who remained in the custody of their parents. Following World War II, these children began to be formally known as "educationally subnormal", and teachers became responsible for recommending them for separate schools. As attitudes towards them changed, the term was taken out of usage in 1981 and attempts were made to integrate them into mainstream schools as much as possible.