Panic is a sudden overwhelming fear that produces hysterical or irrational behavior, and that often spreads quickly through a group of people.
The word "panic" originates from the Greek god Pan, who was believed to cause groundless fear in lonely places.
In modern usage, "panic" can refer to:
1. Panic attack - a sudden episode of intense fear
2. Panic buying - when people buy large quantities of goods due to fear of shortage
3. Panic disorder - a type of anxiety disorder
4. Panic button - an emergency button for summoning help