A walk-up apartment is a type of apartment building in which residents must walk up flights of stairs to reach their units. However, there are several synonyms for the term "walk-up apartment" that can also be used to describe this type of living arrangement. These include "staircase apartment," "upstairs apartment," "multi-level apartment," and "non-elevator building." Each of these terms accurately describes the physical structure of a walk-up apartment and can be used interchangeably. Whether you're a renter or a landlord, it's important to be familiar with these synonyms to effectively describe your living space to potential tenants or buyers.