SAT GRE lunacy Definition Lunacy refers to insanity or extremely foolish behavior. Example "Driving at that speed in the city is pure lunacy." Sign in to save SAT Quiz → GRE Quiz → ← lump lunar → Study tips featuring "lunacy" Spot the Vocabulary Trap in Every Question Write GRE Words Into Your Own Sentences How Context Clues Save You on the SAT Related words SAT abase SAT abdicate SAT abdomen SAT abduction SAT abet SAT abeyance SAT abject SAT abjure SAT ablution SAT abnegate SAT abnormal SAT abominable