Definitions of panic:

• noun:   an overwhelming feeling of fear and anxiety
• noun:   sudden mass fear and anxiety over anticipated events

  Example: "Panic in the stock market"

• verb:   cause sudden fear in or fill with sudden panic

  Example: "The mere thought of an isolation cell panicked the prisoners"

• verb:   be overcome by a sudden fear

  Example: "The students panicked when told that final exams were less than a week away"