A transceiver is one machine that can both send and receive radio signals. Older radio equipment often kept the two jobs in separate boxes — one to transmit, one to receive — so when engineers built them into a single unit they needed a name for it, and they simply pushed the two words together. Everyday examples: the walkie-talkie a security guard carries, the radio set on a fishing boat, a ham radio operator's rig. The word is also used for the small part inside networking equipment that sends and receives data — the little plug-in module in a network switch that turns electricity into light for a fibre cable is called a transceiver, and IT people use the word this way daily. It is a technical word: it lives in manuals, spec sheets and the speech of engineers and radio hobbyists, not in ordinary conversation. Someone holding one in daily life just calls it a radio or a walkie-talkie.