‖a. [ L., fr. duo two + plicare to fold. See Two, and Complex. ] 1. Double; twofold. [ 1913 Webster ]

2. (Computers) organized so that data may be transmitted in two opposite directions over the same channel; -- of communications channels, such as data transfer lines between computers. [ PJC ]

Duplex escapement, a peculiar kind of watch escapement, in which the scape-wheel has two sets of teeth. See Escapement. --
Duplex lathe, one for turning off, screwing, and surfacing, by means of two cutting tools, on opposite sides of the piece operated upon. --
Duplex pumping engine, a steam pump in which two steam cylinders are placed side by side, one operating the valves of the other. --
Duplex querela [ L., double complaint ] (Eccl. Law), a complaint in the nature of an appeal from the ordinary to his immediate superior, as from a bishop to an archbishop. Mozley & W. --
Duplex telegraphy, a system of telegraphy for sending two messages over the same wire simultaneously. --
Duplex watch, one with a duplex escapement. --
half duplex (Computers) (a) arranged so that the information may be transmitted in both directions, but only in one direction at a time; -- of communications channels between computers; contrasted with full duplex(a). (b) arranged so that the information transmitted to the remote computer also appears on the local terminal; -- of communications channels between computers; contrasted with full duplex(b). --
full duplex, (Computers) (a) arranged so that the information may be transmitted in both directions simultaneously; -- of communications channels between computers; contrasted with half duplex(a). (b) arranged so that the information transmitted to the remote computer does not appear on the local terminal; -- of communications channels between computers; contrasted with half duplex(b). [ 1913 Webster ]

v. t. [ See Duplex, a. ] (Teleg.) To arrange, as a telegraph line, so that two messages may be transmitted simultaneously; to equip with a duplex telegraphic outfit. [ Webster 1913 Suppl. ]

n. [ See Duplex, a. ] 1. something which is duplex; -- used mostly in reference to a living unit, such as an apartment, in a building having two similar living units. [ PJC ]

2. (Biology, Genetics) a double-stranded region in a nucleic acid molecule. See deoxyribonucleic acid. [ PJC ]

n. (Radio) a device which switches electronic circuitry so that a radio antenna can function as either a transmitting or receiving antenna. [ PJC ]