- The definition of mysterious is something that is not understood or known.
An example of something mysterious is an old man who lives in a house and never comes outside.
mysterious definition by Webster's New World
Origin: ; from Classical Latin mysterium (see mystery) plush -ous
mysterious definition by American Heritage Dictionary
- Of, relating to, or being a mystery: mysterious and infinite truths.
- Simultaneously arousing wonder and inquisitiveness, and eluding explanation or comprehension: a mysterious visitor; mysterious conduct.
Origin: French mystérieux, from mystère, secret, from Latin mystērium; see mystery1.
- mys·teˈri·ous·ly adverb
- mys·teˈri·ous·ness noun