Multiplex is either a word derived from multi- + plex (fold) or a synthetic portmanteau combining the words multiple and complex and can be another word for many or (literally) manifold.

It has several meanings:

1. A multiplex cinema, or movie theater, is a complex containing several separate auditoriums but sharing such facilities as the box office, refreshment stands, and washrooms.
2. In telecommunications, multiplexing refers to combining many signals (often thousands) into a single transmission circuit or channel.
3. In electronics a device that takes multiple inputs and combines them using time division is called a multiplexer. One concrete example of a multiplexer is the 74ALS157 'Quad 2- to 1-line data selector/multiplexer' integrated circuit. The verb for what this device does is 'to multiplex'. A device that does the reverse function of a multiplexer is called a demultiplexer.
4. A multiplex (broadcast) is a number of digital television or radio channels multiplexed onto a single broadcast channel.
5. Multiplex (wood) is a kind of wood substitute made from wood splinters glued into boards. See also Triplex .
6. A multiplex (road) is a single physical road designated by two or more different highway numbers. If two highways are signed with opposite compass directions along the road, it is a wrong-way multiplex.
7. Multiplex (comics) was a DC Comics character.
8. Multiplex (company) is Australia's third largest property developer[1].