Source : WordNet®

gismo
     n 1: something whose name is either forgotten or not known [syn:
          {dohickey}, {dojigger}, {doodad}, {doohickey}, {gimmick},
           {hickey}, {gizmo}, {gubbins}, {thingamabob}, {thingumabob},
           {thingmabob}, {thingamajig}, {thingumajig}, {thingmajig},
           {thingummy}]
     2: a device that is very useful for a particular job [syn: {appliance},
         {contraption}, {contrivance}, {convenience}, {gadget}, {gizmo},
         {widget}]