Duplex

Duplex is a term used across various fields to denote something that is twofold or two-sided. It comes from the Latin word duplex, meaning double or twofold. The specific meaning depends on the context, but common threads include paired units, bi-directional capabilities, or a two-phase structure.

In architecture and real estate, a duplex refers to a dwelling arranged as two separate housing units within one building, either side by side or stacked one above the other. Each unit typically has its own entrance and facilities, and the design allows two households to share a single structure while remaining privately independent. Duplexes are often used to provide affordable housing or to accommodate extended families.

In printing, duplex printing describes printing on both sides of a sheet of paper. Modern printers with duplex capability can automatically flip the page to print on the reverse side, while older or basic devices may require manual feeding. Duplex printing can reduce paper use and produce more compact documents, though it may require specific page layout considerations.

In telecommunications and networking, duplex describes the ability to transmit and receive data or signals. Full duplex allows simultaneous two-way communication, as in a telephone call. Half duplex permits two-way communication but not at the same time, such as walkie-talkies. The term also appears in networking to describe port and link capabilities, indicating whether a channel supports one- or two-way traffic.

Other uses include duplex stainless steel, a family of alloys with a mixed austenitic–ferritic microstructure that enhances strength and corrosion resistance, and duplex ultrasound, a medical imaging technique combining traditional ultrasound with Doppler flow assessment to visualize blood vessels and blood flow.