ANSWER
Before Rowling invented the word "muggle", purportedly from expanding the Old English word "mug", meaning "fool", the word "muggle" was an American slang term from the 1920's and 30's for a marijuana cigarette. Prior to that, there was also a word "muggle" which meant mist or drizzle, as in a light rain.
WHO GOT IT RIGHT: Bob Milligan, and Marc Quinlivan.
