One would think, with so many people wondering about the roots of “moolah,” that someone would have come up with at least one entertaining “urban legend” about the word, but no such luck.
What theories do exist about its origins are both terse and far-fetched. One holds that “moolah” derives from the French “le moulin,” meaning “the mill,” referring to factory mills as a source of wealth. Color me extremely unconvinced. But while we’re stretching plausibility to the breaking point, I must mention the recent announcement, by the Times of India newspaper, that “moolah” is the Fijian (as in Fiji, in the South Pacific) word for “money.”
Unfortunately, I lent my Fijian dictionary to my accountant last week, so I’ll have to wait until he gets back to check this assertion. But unless someone can explain how a Fijian word ended up on the lips of US gamblers and hipsters in the 1930s, I plan to ignore that theory. Yet another theory traces “moolah” to the Romany (Gypsy) word “mol,” meaning “to be worth,” which is not impossible but is considered unlikely by linguists.
Naw, those sound as hokey as the one that says it is old Spanish slang for "donkey," as apparently donkeys were fairly expensive beasts of burden. The other one that the Word Detective added made more sense-
Another theory, proposed by Daniel Cassidy in his recent book “The Secret Language of the Crossroads: How the Irish Invented Slang,” traces “moolah” to the Irish phrase “moll oir,” meaning “pile of gold.” My inclination is to consider this quite plausible, but Mr. Cassidy apparently paints with a very broad brush, also tracing “buckaroo” to the Irish “bocai rua” (wild boys). It has long been generally accepted, on solid evidence, that “buckaroo” is actually derived from the Mexican Spanish “vaquero,” meaning “cowboy.”