Not known or recognized; strange or not familiar to someone.
Prefix "un-" (not) combined with "familiar" from Latin "familiaris" meaning domestic or well-known. The word is a straightforward negation that emerged in English around the 16th century.
Neuroscience shows that our brains are actually programmed to distrust the unfamiliar—a survival mechanism from our ancestral past when unknown things could be dangerous, which explains why we naturally prefer the familiar!
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