catch-22
noun [ S or U ] uk/ˌkætʃ.twen.tiˈtuː/ us/ˌkætʃ.twen.tiˈtuː/
第22号军规；进退维谷的局面，两难情形
an impossible situation where you are prevented from doing one thing until you have done another thing that you cannot do until you have done the first thing
a catch-22 situation 两难的处境