What does "whatsit" mean?

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

What is a synonym for "whatsit"?

Common synonyms include: thingy, whatchamacallit.

noun

noun ·Rare ·Advanced level

Noun

1
A thing (used in a vague way to refer to something whose name one cannot recall, or that one is embarrassed to say) Ireland, UK
"Pass me one of those whatsits, will you?"

"Pass me one of those whatsits, will you?"

Univerbation of what + is + it.