Insanity, madness, lunacy, and craziness are behaviors caused by certain abnormal mental or behavioral patterns. Insanity can manifest as violations of societal norms, including a person or persons becoming a danger to themselves or to other people. Conceptually, mental insanity also is associated with the biological phenomenon of contagion as in the case of copycat suicides. In contemporary usage, the term insanity is an informal, un-scientific term denoting "mental instability"; thus, the term insanity defense is the legal definition of mental instability. In medicine, the general term psychosis is used to include the presence of delusions and/or hallucinations in a patient; and psychiatric illness is "psychopathology", not mental insanity.

पागलपन एक ऐसी स्थिति होती है जिसमे इंसान अपनी भावनाओं का नियंत्रण नहीं कर पाता है ।ये प्रायः जन्मजात या समाज द्वारा बनाई गई अवस्था होती है जिसमे इंसान खुद या दूसरों को हानि पहुंचाने का प्रयास करता है।