EXTREME FOLLY is a term used to describe a range of behaviors that are considered irrational or foolish. The crossword solutions for this term are LUNACY (6 letters), IDIOCY (6 letters), and INSANITY (8 letters). LUNACY is defined as behavior that is considered to be foolish or irrational, while IDIOCY is defined as a state of extreme mental retardation or foolishness. INSANITY is defined as a severe mental disorder that impairs one's ability to think, reason, and understand reality. All three terms are used to describe extreme folly and can be used interchangeably.