In the fictional world of J. K. Rowling's book series Harry Potter, a muggle is a person who lacks any sort of magical ability and was not born into the magical world. Muggles also do not have any magical blood. It differs from the term Squib, which refers to a person with one or more magical parents yet without any magical ability, and from the term Muggle-born (or the more offensive mudblood), which refers to a person with magical abilities but without magical parents.
Read more about Muggle: Usage in Harry Potter, Later Usages