A studio apartment is a small, self-contained living space that generally comprises a single room serving multiple functions. However, there are a few synonyms to describe this type of apartment, such as a bachelor apartment, efficiency apartment, or an open-plan apartment. A bachelor apartment is similar to a studio apartment, but it specifically refers to living quarters for a single, male occupant. The term "efficiency" refers to an apartment that is typically smaller than a studio and usually contains a single combined living, sleeping, and cooking area. The phrase "open-plan apartment" refers to the layout of a space that incorporates an open floor plan, without any interior walls separating the different areas of the apartment.