Throughout history, rich and poor alike have endowed their money with a series of expressive nicknames. Centuries of imaginative thought have given us a chance to gripe about how there's never enough clams, dinero, bread, dough, greenbacks, or dead presidents in the bank. While I can't tell you where the money comes from, I can at least tell you where we got the term. Long ago, on one of the seven hills of ancient Rome, there stood a temple called Juno Moneta, or "Juno who warns". Juno was the Roman God of woman and childbirth (in case you were wondering why the young, pregnant protagonist of the 2007 film got her name). She was deemed "Juno who warns" after a flock of noisy geese perched in her temple woke nearby Romans to discover a fire. It just so happened that the Roman mint was located within the temple to Juno, and over time the mint came to be referenced as "ad Monetum" or "at the temple of (Juno) Moneta)". It followed that the coins the mint produced were nicknamed "moneta." The term endured ages of linguistic childbearing in the Romance Language Family to survive in Spanish (moneda), French (monnaie), Italian (moneta), and even in our Germanic English as the term we know, love and can't seem to stop talking about.
<- Roman denarius featuring the image of Juno and the phrase "Moneta"