Thingamajig /noun / thing·a·ma·jig
A thingamajig is an unidentified or mysterious machine, device, apparatus, or toy that first appeared in print in the early 18th century. The Oxford English Dictionary defines it as "a mechanical contrivance seemingly complex and enigmatic; a puzzling assemblage of parts."
This word has been used frequently in popular culture over the years and can be found in books, movies, TV shows, etc. Most often, it is used to describe something strange or unexplainable.
In a Sentence
I was curious about the thingamajig my neighbor was building in his backyard, so I decided to take a look — it seemed like nothing more than a pile of junk — until I discovered it could spin!
Thingamajig can also refer to something strange or unexplainable that intrigues us and prompts us to investigate further.
I was trying to figure out what this thingamajig on my refrigerator was supposed to do, but I had no idea.
The word thingamajig comes from the North American English word thing-a-ma-jigger, which is a term that was first used in the late 1830s. The Oxford English Dictionary defines it as a dialectal variant of thingamajig, meaning something mysterious or puzzling.
Doodad, Doohickey, Thingumabob
Plain, Explainable Object