A warning signal (such as the call of sentry, the ringing of a bell, or the shriek of a siren) which turns out to have been given erroneously.
A thing or occurrence which initially causes fear, distress, etc. but which is subsequently recognized as being no cause for concern.
Anything deliberately intended to deceive or trick.
To deceive (someone) by making them believe something that has been maliciously or mischievously fabricated.