Sentence:  Bush, even when he had the floor, grimaced as he spoke, except on several occasions when he lost his way and a look of total <WSD>erasure</WSD> came over him, a blank, stricken stare for which the French, alas, have the most apt expression: like a cow watching a train go by. 
Meaning of the word marked with <WSD> tags:  The state of having been erased; total blankness.