The English idiom the World's second oldest profession is used to refer to a number of professions. One frequent use of the phrase is to refer to spies and spying. An explanation of this phrase is that it must be the second oldest profession because it is mentioned in the bible.

Ronald Reagan nominated politician as the second-oldest profession with the quip "It's been said that politics is the second oldest profession. I have learned that it bears a striking resemblance to the first."

Other frequently named professions are doctor, philosopher, lawyer, soldier, merchant and farmer.