thingumajig - noun

something unspecified whose name is either forgotten or not known

thingumajig - thesaurus

doodad   doohickey   doojigger   gimmick   gismo   gizmo   gubbins   thingamabob   thingamajig   thingmabob   thingmajig   thingumabob   thingummy   whatchamacallit   whatchamacallum   whatsis   widget