proverbial
adj.adj. describes something that is very famous or well-known because people often talk about it or mention it in old sayings. You use it to refer to a common idea that everyone already understands.
adj. relating to or resembling a proverb; widely referred to or well-known. Often used to introduce a cliché or a common cultural reference.
He is the proverbial early bird who always arrives first.
The team's failure was the proverbial final straw that led to the manager being fired.
By the time the rescue party arrived, the proverbial needle in a haystack had been found by a local farmer who knew the terrain intimately.
From Latin prōverbiālis, equivalent to proverb + -ial
Typically used attributively before a noun to signal that the speaker is using a common metaphor or idiom.