lunatic

As for Cordelia, she went insane with remorse and was shut up in a lunatic asylum.

In neither case were there any signs which could give us a clue as to the criminal or lunatic who had done the mischief.

Tell him for me that I have quite made up my mind, and that it is certain that a dangerous homicidal lunatic, with Napoleonic delusions, was in his house last night.

“I say, Watson,” he whispered, “would you be afraid to sleep in the same room with a lunatic, a man with softening of the brain, an idiot whose mind has lost its grip?”