A Non-Magical Human is a human who is incapable of performing magic, but is not a Squib. These comprise the majority of the world's citizens, and are typically unaware of the existence of the magical community. There is no true universal term for Non-Magical Humans, as each wizarding community in each country has different terms for them.
Non-Magical Human terms
The Commonwealth of Australia
In Australia, Non-Magical Humans were referred to as "Normal" at one point in time, with "Normals" being the plural. However, like the United States of America would later do, the term was corrupted over time to simply "Normie", with the plural being "Normies" or even "Ns" as slang.
The Federal Republic of Germany
In Germany, the Wizarding community does not use the term "Muggle", but instead adopts the term "Machtlos", which means "powerless" in the German language, among other meanings. "Machtlos" has no plural variant, and can be used to refer to one or more "Machtlos".
The United Kingdom of Great Britain and Northern Ireland
In the United Kingdom, Non-Magical Humans are referred to as a "Muggle", with "Muggles" being the plural. It is unknown when the term "Muggle" first came about, but it has been in use by the majority of Wizarding Europe for centuries.
The United States of America
In the United States, the term "Muggle" is used far less commonly, having been dropped by the descendants of the first English settlers at an unknown point in time. The term "No-Magic" was adopted at an unknown point in American wizarding history, and was eventually corrupted into "No-Maj", which is now the common vernacular. "No-Majs" or "No-Majes" is the known plural.
The United Mexican States
In Mexico, the term for a Non-Magical Human was contracted from the original term "Sin Magia" — literally meaning 'Without Magic' — to "Si-Mag". The plural for this term is "Si-Mages". It is notably similarly to the term used in the United States of America, and this is possibly due to both countries eventually coming to share the same school.
- Muggle on Harry Potter Wiki