A word used when the actual name of the object in question will not come to mind. Very versatile but often very vague. It is derived from the phrase "what-you-may-call-it" which can be found in T. H. White's The Once and FutureKing.
Claire- "Hey, Adam, hand me the- the- you know, the whatchamacallit."
This word can refer to and be used in place of any noun in the english language. Usually used to substitute for an unkown word when the speaker or writer is confused about the proper noun. This word was first used in 1964 when "Screwy Louie" asked a padestriant for directions to some place he couldnt recall the name of.
Person 1- Um, could you tell me how to get to the Wachacallit?
Person 2- Sure. Just stand in the middle of the road, bend over, and grab your ancles.