In popular usage " a basket case" refers to someone in a hopeless mental condition, but in origin it had a physical meaning. In the slang of the British army during World War I, it referred to a quadruple amputee. This is one of several expressions that first became popular in World War I, or that entered American army slang from British English at that time. Examples: After his wife left him, he became a total basket case. She became a basket case when she failed her final exam.

"basket case" is slang for mentally disturbed, a crazy person

It means someone emotionally or mentally unstable - usually as a result of some traumatic event. Apparently it originally referred to WWI soldiers who had lost arms or legs in battle, ie. incapacitated and unable to function as before. The image is that they had to be carried off the battlefield in a "basket".

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