The definition of mysterious is something that is not understood or known.(adjective)
An example of something mysterious is an old man who lives in a house and never comes outside.
See mysterious in Webster's New World College Dictionary
Origin: < L mysterium (see mystery) + -ous
See mysterious in American Heritage Dictionary 4
Origin: French mystérieux
Origin: , from mystère, secret
Origin: , from Latin mystērium; see mystery1.
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