In Harry Potter, Muggles are persons without magical ability born outside of the magical community. The term is almost always derogatory. Always use in conjunction with the [harry-potter] tag and any relevant tags.
Muggles (a word coined by J.K. Rowling), in the Harry Potter universe, is the term used by magic users for persons without magical ability born outside the magical community. They are generally ignorant of the magical activity going on around them, taking little notice of Witches and Wizards as the Muggle world goes about its business.