- A house with two separate dwelling units sharing the same parcel of land. See also duplex house, two-family house.
- Consisting of two parts or elements, especially those which work together.
- Two-way communication which occurs simultaneously in both directions. Also called duplex communication (1), full-duplex, or two-way communication (2).
- Two-way communication in which communication can only occur one direction at a time. Also called duplex communication (2), half-duplex, or two-way communication (3).