gismo (
http://definr.com/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 very useful for a particular job [syn:
appliance,
contraption,
contrivance,
convenience,
gadget,
gizmo,
widget]