whatchamacallit

noun

Etymology: Univerbation and contraction of what you may call it. United States, 20th century (recorded in 1921).

1. A metasyntactic term used for any object whose actual name the speaker does not know or cannot remember; a doodad, gizmo, thingamajig, thingy.

   “The Thingamajig and the Wachamacallit.”

   “You’re—you must be the whatchamacallit, huh? The peer.”