punctum caecum

1923, Ernest Bramah, The Eyes of Max Carrados It was perhaps three minutes later when an excited gentleman in the state of disrobement that is tacitly regarded as falling upon the punctum caecum in times of fire, flood and nocturnal emergency shot out of the door of No. 7 and bounding up the intervening flights of steps pounded with the knocker on the door of No. 9.