A penthouse apartment is typically a luxurious, high-end living space located on the top floor of a building. However, there are several other terms that can be used to describe this type of living space. For instance, a "sky mansion" can be used to describe a particularly opulent penthouse apartment, while a "rooftop retreat" may be a more peaceful space to relax and enjoy the views. A "top-floor flat" or "high-rise loft" are also common alternatives for a penthouse apartment. Ultimately, whichever term is used to describe these exclusive, high-end living spaces, they are highly coveted for their excellent views, supreme comfort, and exceptional luxury.