If I were to define the term "worthless," I would define it as "worth LESS" or "worth not a lot."
But the actual dictionary definition is something like "worth zero." That's even less than "worth less" or "worth-not-a-lot."
How did the term come by its actual connotation. Could "less" in this context be a play or derivative of the German "los?" (The German Wertlos has the same meaning as the English worthless.)