175 False alarm
(PW) warning or report that is untrue
She thought that she was pregnant, but it was a false alarm.
(free) n.
1. An emergency alarm, such as a fire alarm, that is set off unnecessarily.
2. A signal or warning that is groundless.
n
1. a needless alarm given in error or with intent to deceive
2. an occasion on which danger is perceived but fails to materialize
(dictionary)
1. a false report of a fire in progress to a fire department.
2. something that excites unfounded alarm or expectation: Rumors of an impending transit strike proved to be a false alarm.