J.K. Rowling used the word “Muggle” for a non-magical person in the Harry Potter series.
In the books, a Muggle is someone who lacks magical ability and is not part of the wizarding community. The word is used throughout the series for characters such as Vernon and Petunia Dursley, although Harry himself is magical despite being raised in a Muggle household.
“Muggle” is not the same as “Squib.” A Squib is a person born into a wizarding family who cannot perform magic, while a Muggle has no magical ancestry in the usual sense. “Mudblood” is a derogatory term for a witch or wizard born to non-magical parents, not a synonym for Muggle.
Rowling’s use of the term helped it enter wider popular culture. In 2003, “muggle” was added to the Oxford English Dictionary with its Harry Potter-related meaning.