Sentence:  It is claimed that 20 per cent of children will have an <WSD>intellectual disability</WSD> at some time in their lives, which may result from medical problems, sensory impairments, hysical disabilities, emotional and behavioural difficulties, language impairments, or specific learning problems such as dyslexia or autism [Emerson et al. 2001:7]. 
Meaning of the word marked with <WSD> tags:  Any disability that affects the intellect or cognitive ability of a person.