The word "telex" is a 20th-century portmanteau, a blend of the existing English words "teleprinter" and "exchange." The first element, "tel," is derived from the Greek prefix tēle-, meaning "far," which was already widely used in telecommunications terminology like "telegraph" and "telephone" to denote operation over a distance. The second element, "ex," is a direct truncation of the English word "exchange," referring to a central switching system that connects multiple users. Thus, the term literally and logically describes a "distant exchange" system, where messages are transmitted over long distances and routed through a network, evolving from a specific brand name into the generic term for the technology.

Structure: tel (distance) + ex (exchange) - tel: From Greek tēle-, meaning "far off, at a distance." It functions as a combining form indicating distance. - ex: A shortened form of "exchange." It functions as the core noun specifying the type of operation or system.