thingummy - noun

something unspecified whose name is either forgotten or not known

thingummy - thesaurus

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