Definition of Catch-22 from the Oxford Advanced Learner's Dictionary

Catch-22

 
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a comic but serious US novel (1961) about the madness of war. It was written by Joseph Heller (1923–1999), and a film version was made in 1970. The story is about a US Air Force pilot during World War II. He hates the war and tries to avoid having to fly planes. The book was a great success with US students in the 1960s. The expression Catch-22 has now entered the English language, meaning an unpleasant situation from which you cannot escape because you need to do one thing before doing a second, and you cannot do the second thing before doing the first
We’re in a Catch-22 situation.There was only one catch and that was Catch-22, which specified that a concern for one’s own safety in the face of dangers that were real and immediate was the process of a rational mind … Orr would be crazy to fly more missions and sane if he didn’t, but if he was sane he had to fly them. If he flew them he was crazy and didn’t have to; but if he didn’t want to he was sane and had to.