|1.||a needless alarm given in error or with intent to deceive|
|2.||an occasion on which danger is perceived but fails to materialize|
A warning signal that is groundless, made either by mistake or as a deliberate deception. For example, The rumor that we were all going to get fired was just a false alarm, or Setting off a false alarm is a criminal offense. This expression, first recorded in 1579, today is often used for a report of a nonexistent fire.