ˌHail ˈMary pass BrE AmE ( also ˌHail ˈMary play ) noun [countable] American English
1 . in American football, a long throw forward that you hope will be caught successfully, although it is unlikely, so that your team will score a point when you do not have much time to do this
2 . an action you take that is unlikely to succeed, and which you only take because there is no other way of achieving something