Whatchamacallit (noun)

A thing whose name is not known or remembered.

Origin:

The word "whatchamacallit" is a colloquialism, meaning a thing whose name is not known or remembered.

Examples:

1. Can you pass me that whatchamacallit over there?
2. I can't remember the name of that whatchamacallit, the thing you use to open bottles.
3. I'm looking for that whatchamacallit, you know the thing that we use to fix the car.
4. I think it"s called a whatchamacallit, but I"m not sure.
5. I need a new whatchamacallit for my phone, the thing you plug in to charge it.