Noun

(en noun)

(colloquial) A substantial mistake, usually causing problems for more people than just the person or group who made it.

*{{quote-book

, year=1977 , author=John Osborne , title=White House watch: the Ford years? , page=147 , passage=The Ford administration emerged in better shape than it deserved from the fantastic screw-up that preceded the release of the Rockefeller...}}

(colloquial) A person who often makes substantial mistakes.