Alps

This term refers specifically to the European mountain range and is always capitalized as a proper noun. It is used as a collective name for the entire system, though it is grammatically plural in form.

Because it is a proper name for a specific geographic entity, it does not function as a common noun. It is never used to describe generic alpine mountains in other parts of the world unless used as a modifier (e.g., "the Japanese Alps"), in which case it retains its plural structure.