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