noun (n)

• a drawback or difficulty that is not readily evident(noun.attribute)

  Synonym:
  catch
  

  source: wordnet30
• something unspecified whose name is either forgotten or not known(noun.artifact)

  Synonym:
  doodad, doohickey, doojigger, gismo, gizmo, gubbins, thingamabob, thingamajig, thingmabob, thingmajig, thingumabob, thingumajig, thingummy, whatchamacallit, whatchamacallum, what
  

  source: wordnet30
• any clever maneuver(noun.act)

  Example:
  It was a great sales gimmick.
  A cheap promotions gimmick for greedy businessmen.
  

  Synonym:
  device, twist
  

  source: wordnet30