1) Keeps from entering 2) Prevents from scoring 
When you lose a game without ever scoring in it.
[horse] The year Shut Out was born Greentree Stables also produced Devil Diver who would eclipse Shut Out in fame and achievements, yet it was Shut Out who won both the 1942 Kentucky Derby and the Belmont Stakes under jockey Wayne D. Wright. Devil Diver beat Shut Out in the 1941 Hopeful Stakes for 2-year-olds. But Shut Out proved the better...
To hold the opposition scoreless for an entire game or any specified period of time; e.g., 'the brui