or what·cha·ma·call·it, what-you-may-call-it, what-do-you-call-it
[hwuhch-uh-muh-kawl-it, hwoch-, wuhch-, woch-]
an object or person whose name one does not know or cannot recall.
Origin of whachamacallit
1940–45; spelling of what you may call it reflecting affrication of t before y and reduction of vowels; compare similar metric pattern and internal əmə in rigamarole, thingamagig
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019