Which term refers to a room or set of rooms for living in a larger building?

The term that refers to a room or set of rooms for living in a larger building is indeed "apartment." An apartment typically consists of multiple rooms designed for residential living, which may include a bedroom, bathroom, kitchen, and living area. The defining characteristic is that it is part of a larger structure that is owned collectively by multiple apartment owners or a property management company, with each apartment being privately owned or rented by an individual tenant.

In contrast, while a condominium also refers to a living space within a larger building, the key difference lies in ownership; condominiums are individually owned units within a larger complex where common areas are jointly owned. A studio generally refers to a compact living space that is typically a single room serving multiple functions—living, cooking, and sleeping—without separate bedrooms. The term flat is often used interchangeably with apartment in certain regions, but it does not capture the full spectrum of residential spaces that "apartment" encompasses, particularly in the context of North American usage.

Understanding the distinctions among these terms helps clarify what constitutes an apartment, particularly in discussions about urban living and residential structures.