muggle [L20th] This word is best known as the term used for someone without magical powers which first appeared in J. K. Rowling’s Harry Potter and the Philosopher’s Stone in 1997, but which was being used more generally of someone lacking a particular skill within two years. It is formed from *mug in the sense of ‘a stupid or incompetent person’. Perhaps disconcertingly, muggle has also been used for marijuana or a joint since the 1920s.