Entry 1 sense Webster, 1913

whatchamacallit

· IPA /ˈwʌt͡ʃəməˌkɔlɪt/

01 n. Any object whose name is forgotten, or not known.

1.
Any object whose name is forgotten, or not known.

Syn. thingumbob, doohickey, dingus, whatsis, what-do-you-call-it.