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Definition of "insanity" []

  • Mental illness or derangement. No longer in scientific use. (noun)
  • Law Unsoundness of mind sufficient in the judgment of a civil court to render a person unfit to maintain a contractual or other legal relationship or to warrant commitment to a mental health facility. (noun)
  • Law In most criminal jurisdictions, a degree of mental malfunctioning sufficient to relieve the accused of legal responsibility for the act committed. (noun)
  • Extreme foolishness; folly. (noun)
  • Something that is extremely foolish. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Use "insanity" in a sentence
  • "Dr Jones was also frankly appalled by the use of the term insanity with regard to the king as the label was enough to destroy a mans credit and happiness for ever."
  • "Our view is that we've been trying to get the market to solve cybersecurity for years, and we don't want to repeat the definition of insanity, which is continuing to do the same thing over and over again and expecting a different outcome."
  • "But their efforts to address the looming long-term care financial problem should not be associated with the word "insanity," nor should the forthright efforts of Health and Human Services Secretary Kathleen Sebelius, who has held to her commitment not to foist an unsustainable program on future American taxpayers."