adjective

• missing or misplaced.

  My car keys are 404.

  More words meaning: computer slang
  More words meaning: lost, missing, misplaced

  by Eric B., Fort Worth, TX, USA, Aug 10 1998  (Edit definition)

noun

• an unintelligent person; MORON, DIMWIT.

  I wouldn't ask him, he's a 404.

  More words meaning: computer slang
  More words meaning: unintelligent person, idiot

  by Walt W., Natick, Massachusetts, USA, Jun 17 2003  (Edit definition)

• a worthless person, place, or thing.

  Don't go to that bar - it's a 404.

  More words meaning: bad, poor, sucks, common, generally displeasing
  More words meaning: computer slang
  More words meaning: uncool person, jerk, asshole (general insults - list of)

  by Robbie G., Stroud, Hampshire, UK, Feb 13 2006  (Edit definition)

verb

• to not know or temporarily forget; DRAW A BLANK.

  I'm 404ing on that.

  More words meaning: computer slang
  More words meaning: to forget

  by The Jargon File, Aug 04 2009  (Edit definition)

origin

• 404 is the web code for "web page not found."

  by Anonymous, Jul 17 2007  (Edit definition)