Likely from the Belgian city Arlon, possibly of Celtic origin meaning 'near the forest'.
Arlon carries the quiet distinction of being the name of the oldest city in Belgium — a settlement in the Ardennes whose history predates the Roman Empire and whose Latin name, Orolaunum, was itself a Latinization of a Gaulish or pre-Celtic place name whose precise meaning has been debated by historians for centuries. Arlon the city was a crossroads of the ancient world: Roman legions passed through it, Frankish kings administered it, and the dense forest around it became the Ardennes of medieval legend and, eventually, of the Second World War's Battle of the Bulge.
As a given name, Arlon appears in American records primarily from the nineteenth and early twentieth centuries, used as a first name with the confident simplicity that that era brought to surname-derived and place-derived names. It shares its sonic shape with Aaron (Hebrew, "exalted" or "high mountain"), Harlan, and Orlan, and sits comfortably in the company of names like Merlon, Carlon, and Arlen — a family of names that were quietly widespread in rural America before falling out of fashion and now carrying the particular appeal of the genuinely vintage. For contemporary parents, Arlon offers a name that is easy to pronounce in any language, strong without being aggressive, and connected — for those who follow the thread — to one of Europe's most layered historical crossroads. It sounds modern in the way that only very old things can: not because it has been polished, but because it has been worn smooth by time into something essential.