whatchamacallit[hwuc̸h′ə mə kôl′it, wuc̸h′-]
whatchamacallit definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
Origin: ; from what you may call it
whatchamacallit definition by American Heritage Dictionary
Something whose name has been forgotten or is not known.
Origin: Alteration of what you may call it.