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His language is of course hyperbolic, but that suggests more the culture in which he has worked for many years than mental deficiency.

Whatever his mental deficiencies, he doesn't seem the sort to go down without a fight.

By the 1920s the hospital was operating school clinics to help determine mental deficiency in children.

Are you suffering from some sort of I don't know mental deficiency?

The English family he studied with the inherited language disorder often had mental deficiencies as well.

She, on the other hand, found herself treated like a princess, or someone with severe mental deficiencies, by all the household staff.

Here Goddard made a distinction between two levels of mental deficiency.

He "considers happiness to be a form of mental deficiency."

The glazed look on her face was not mental deficiency.

During the 1890s, amentia meant someone who was born with mental deficiencies.