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.
1620s, "one side of a multi-sided body," from French facette (12c., Old French facete), diminutive of face "face, appearance" (see face (n.)). The diamond-cutting sense is the original one. Transferred and figurative use by 1820. Related: Faceted; facets.
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<a href="https://www.etymonline.com/word/multifaceted">Etymology of multifaceted by etymonline</a>
Harper, D. (n.d.). Etymology of multifaceted. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/multifaceted