The Collaborative International Dictionary of English v.0.48:

black out \black out\ v. i.
   to experience a temporary loss of consciousness, memory, or
   vision.
   [PJC]

The Collaborative International Dictionary of English v.0.48:

black out \black out\ v. t.
   1. to cause to become black, such as a stage, a computer
      screen, or a city.
      [PJC]

   2. to impose a blackout on (news or a sports event).
      [PJC]

   3. to make (a written text) illegible by applying a black ink
      over it; to blot out.
      [PJC]

   4. to suppress (a memory).
      [PJC]

WordNet (r) 3.0 (2006):

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:
       black out, 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, black out]

Moby Thesaurus II by Grady Ward, 1.0:

65 Moby Thesaurus words for "black out":
   annul, becloud, bedarken, bedim, begloom, black, blacken,
   block the light, blot out, brown, cancel, cast a shadow, censor,
   cloud, cloud over, crap out, darken, darken over, delete, dim,
   dim out, drop, eclipse, efface, encloud, encompass with shadow,
   expunge, faint, fall senseless, gloom, gray out, hugger-mugger,
   hush, hush up, hush-hush, keel over, kill, muffle, murk, obfuscate,
   obliterate, obnubilate, obscure, obumbrate, occult, occultate,
   overcast, overcloud, overshadow, pass out, quash, repress, shade,
   shadow, shush, sit on, smother, somber, squash, squelch, stifle,
   succumb, suppress, swoon, wipe out