1. The phrase "n'appartient pas" is French and translates to "does not belong" in English. 2. In mathematics, it is often used to indicate that an element is not a member of a set. 3. For example, if $x \notin A$, it means $x$ does not belong to the set $A$. 4. So, "n'appartient pas" means the element is not included in the specified set or group.