Thingamajig (noun)

A term used to refer to an object or device whose name one cannot recall or is not known.

Origin:

The origin of the word "thingamajig" is uncertain, but it is thought to be a fanciful or playful word first used in the early 19th century, likely as a combination of the words "thing" and "whatchamacallit".

Examples:

1. I can"t remember what it"s called, but you know, that thingamajig that you use to open bottles.
2. I need to buy a new thingamajig for my bike, the old one broke.
3. My son is always playing with that thingamajig, I don't know what it does.
4. I'm looking for my thingamajig, have you seen it?
5. Can you hand me that thingamajig over there?