Gizmo and Whatsit

Gizmo noun - An interesting and often novel device with a practical use.

Whatsit and gizmo are semantically related In some cases you can use "Whatsit" instead a noun "Gizmo".

Whatsit noun - A small article the actual name of which one either does not know or cannot remember.

Gizmo and whatsit are semantically related in whatnot topic. You can use "Gizmo" instead a noun "Whatsit".