noun
doohickey
DOO-hik-ee/ˈduːhɪki/
A gadget or object whose name is unknown or forgotten.
He holds the doohickey while trying to recall its name.

Etymology
Doohickey is an arbitrary name for something the speaker cannot name. Its placeholder function is documented, but the supplied evidence gives no roots explaining its form.
In context
we find a doohickey on the top floor that projects an image of the Chinese dragon on the wall which reveals a hidden door
More examples
- He used a plastic doohickey to open the battery cover.
- I found the missing doohickey beneath the workbench.
- She attached the doohickey but could not remember its name.
Forms
doohickey · doohickeys
Similar words
- thingamajig
- Thingamajig is another informal placeholder for a forgotten object name.
- gadget
- A gadget is a small useful device; doohickey also signals that its name is unknown or unimportant.