A duplex is a type of building or apartment that has two separate living units, usually connected by a shared wall. It is also known as a DOUBLE occupancy dwelling or a semi-detached dwelling. The term 'duplex' comes from the Latin word for 'DOUBLE, ' and it is used to describe a structure that has two distinct living spaces. Duplexes are often found in urban areas, where they provide an affordable housing option for people who want to live close to the city center.