(a) a fruit (now usually identified with that of the mudar, Calotropis procera (family Asclepiadaceae)) which, according to legend, appears…

A cause of disappointment; a thing which or person who disappoints.

slang. A deception; a disappointing event or result. Also suck-in.

By extension: A descent or fall in contrast to a previous rise.

slang. A contrivance, fiction, etc., by which a person is ‘sold’: a planned deception, hoax, take-in. Also, something that utterly disappoints…

slang (originally U.S.). Something which is bad or undesirable or which fails to meet one's expectations.

figurative or in figurative contexts. damp squib, something that fails ignominiously to satisfy the expectations aroused by it; an anti-climax, a…