whatchamacallit
noun
°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.
synonyms: dohickey, doohickey, doober, doodad more» , doover, doomaflatchy, gizwiz, jobbyjobber, thingamabob, thingumabob, thingummybob, thingamajig, thingo, thingummy, whatnot, whatsit