Longman Dictionary of Contemporary English
Wiktionary
n. 1 (context idiomatic English) One who is in serious danger or trouble. 2 (context idiomatic English) A project that is doomed to failure from the start.
WordNet
n. something doomed to failure; "he finally admitted that the legislation was a dead duck"; "the idea of another TV channel is now a dead duck"; "as theories go, that's a dead duck"
Usage examples of "dead duck".
Again,, as President, he has to give a lead to the nation-if he refused to eat while his oil friends did, he'd be a dead duck at the next election.
If I gave it more than another five minutes on board this rig they'd have a dead duck.
Butcher Bird, I'll bet y'father was a dead duck an' your mother was a half-shot cuckoo!
Whoever had shot at me must have figured I was a dead duck, because he just let me lay.
No one can make a dead duck go 'quack' any more than a dead person can be made to speak.
He was awakened before dawn, not by Avatre, but by a dead duck falling on his head.