Synonyms For "Thingummy" :

2 syllables:

doodad, gimmick, gismo, gizmo, gubbins, whatsis, widget

3 syllables:

doohickey, doojigger, thingmabob, thingmajig

4 syllables:

thingamabob, thingamajig, thingumabob, thingumajig

5 syllables:

whatchamacallit, whatchamacallum