معنی کلمه A basement apartment

When I was in college, I was living in a dark basement apartment.

A basement apartment is an apartment located below street level, underneath another structure—usually an apartment building, but possibly a house or a business

What are the disadvantages of living in a basement?
3 Basement Cons

Basements and cellars in residential properties of all sizes can NEVER be lawfully rented or occupied unless the conditions meet the minimum requirements for light, air, sanitation and egress, and have received approval by the Department of Buildings (DOB).

They probably want more privacy and maybe an outside entrance. Maybe they want to cook their own food, or have more room to have guests over. The basement is like a separate apartment in many cases. It provides some semblance of independent living.