noun (n)

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

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

  source: wordnet30
• a device or control that is very useful for a particular job(noun.artifact)

  Synonym:
  appliance, contraption, contrivance, convenience, gadget, gizmo, widget
  

  source: wordnet30