Whatsit vs. Doohickey — What's the Difference?

Something whose name is unknown or forgotten.

Something, especially a small device or part, whose name is unknown or forgotten.

A thing (used in a vague way to refer to something whose name one cannot recall, or that one is embarrassed to say)

(slang) A thing used in a vague way to refer to something whose name one does not know or cannot recall

Any object, usually a tool or other device, whose name is forgotten, or not known.

Something whose name is either forgotten or not known