australian english and new zealand english traditionally used the term "flat" (although it also applies to any rental property), and more recently also use the terms "unit" or "apartment". in australia, a 'unit' refers to flats, apartments or even semi-detached houses. in australia, the terms "unit", "flat" and "apartment" are largely used interchangeably. newer high-rise buildings are more often marketed as "apartments", as the term "flats" carries colloquial connotations. the term condominium or condo is rarely used in australia despite attempts by developers to market it.