before vowels mult-, word-forming element meaning "many, many times, much," from combining form of Latin multus "much, many," from PIE *ml-to-, from root *mel- (2) "strong, great, numerous." It was much-used in forming Latin compounds in classical times and after (such as multianimis "having much courage," multibibus "much-drinking," multicomus "having much hair," multiloquus "talkative"). Many English words that use it (multinational, etc.) are 20c. coinages.
"newspapers, radio, TV, etc." 1927, perhaps abstracted from mass-media (1923, a technical term in advertising); plural of medium (n.) as "intermediate agency," a sense attested in English from c. 1600. Also see -a (2).
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Definitions of multimedia from WordNet
transmission that combine media of communication (text and graphics and sound etc.);