multi- Look up multi- at Dictionary.com
before vowels mult-, word-forming element meaning "many, many times, much," from comb. form of Latin multus "much, many," from PIE *ml-to-, from root *mel- (4) "strong, great, numerous" (source also of Latin melior "better," Greek mala "very, very much"). Many words that use it (multinational, etc.) are 20c. coinages.