A profound degree of intellectual sub-normality in which the affected individual can do nothing for himself and cannot speak. The term is now obsolete, but roughly corresponds to an intelligence quotient of less than 20. There are usually associated physical handicaps and there is always physical damage of the brain.
Any severe mental deficiency apparent in early childhood. The cause, which occurs either in utero or in the first years after birth, may be genetic or traumatic or due to severe insults to the brain.