Source : WordNet®

black out
     v 1: obliterate or extinguish; "Some life-forms were obliterated
          by the radiation, others survived"
     2: darken completely; "The dining room blackened out" [syn: {blacken
        out}]
     3: suppress by censorship as for political reasons; "parts of
        the newspaper article were blacked out"
     4: lose consciousness due to a sudden trauma, for example [syn:
         {zonk out}, {pass out}]