That little "/" separating your fractions? It used to be money. Actual, spend-it-at-the-market Roman gold money. The word solidus names both the sloping line and the ancient coin. Same word. Not a coincidence.

From Gold to Silver to Scribble

The solidus coin was prestigious enough that it lent its Latin name to a whole generation of medieval descendants: Byzantine, Carolingian, Italian, and the English shilling. Most of those heirs were silver, which feels like a demotion, but the name traveled with them anyway.

The English shilling needed a shorthand. The obvious move was abbreviating it to its first letter. That first letter was the "long s," written as ſ, a form that looks like a slash mark with aspirations. Scribes being scribes, the long s got flattened into a simple slash. The word solidus followed the symbol over and stuck.

The OED defines solidus (sense 2) as a sloping line used to separate shillings from pence, as in 12/6, in writing fractions, and for other separations of figures and letters. Its first citation for that meaning comes from 1891, in the Century Dictionary. The Century Dictionary's own entry for solidus is dated 1913. A small bibliographic puzzle worth noticing.

The Relatives Are Surprising

Solidus is a doublet of: sol, sold, soldo, solid, sou, and xu.

That list is doing serious work. Solid as in reliable, stable, hard. Sou as in the French coin. Xu as in one hundredth of a Vietnamese dong. All of them descend from the same Roman gold coin.

Next time someone tells you etymology is too academic, show them that a "/" and the word "solid" share a great-great-grandparent, and that grandparent also spawned a subunit of Vietnamese currency. The family reunion would be chaotic.

The Word Worth Knowing

The "/" on your keyboard has been called a slash, a forward slash, a stroke, a virgule, and a fraction bar. Solidus is the one with the Roman gold behind it. The one with the story. Words with good stories stick. This one should stay with you.

Type a URL today and you will use it twice before the domain name even starts.

Source: Languagehat