What does the word demented mean?

Usage examples for demented

  1. Think me demented- it's your right; but don't tell anybody why." – Embarrassments by Henry James
  2. To Paul the room seemed demented because there was dust on the books and because the basket full of torn paper had not been emptied. – The Twilight of the Souls by Louis Couperus
  3. Domestic cattle and horses often eat this plant; where it is abundant, and become demented in consequence. – The Extermination of the American Bison by William T. Hornaday