doodad, doohickey, doojigger, gimmick, gizmo, gismo, gubbins, thingamabob, thingumabob, thingmabob, thingamajig, thingumajig, thingmajig, thingummy, whatchamacallit, whatchamacallum, whatsis, widget(noun)

something unspecified whose name is either forgotten or not known

"she eased the ball-shaped doodad back into its socket"; "there may be some great new gizmo around the corner that you will want to use"

thingmabob(Pronoun)

A word used to refer to an item for which one does not know or cannot recall the name.