noun /ˈwɒtʃ.ə.mə.kɔːl.ɪt,ˈwʌtʃ.ə.mə.kɑl.ɪt/
a metasyntactic term used for any object whose actual name you don’t know or can’t remember. There are many spellings and many synonyms.
Syn: dohickey, doohickey, doober, doodad, doover, doomaflatchy, gizwiz, jobbyjobber, thingamabob, thingumabob, thingummybob, thingamajig, thingo, thingummy, whatnot, whatsit
Wikipedia foundation.