/ Dictionary / Index M mysterious: Meaning and Definition of Find definitions for: mys•te•ri•ous Pronunciation: (mi-stēr'ē-us), [key] — adj. full of, characterized by, or involving mystery: a mysterious occurrence. implying or suggesting a mystery: a mysterious smile. of obscure nature, meaning, origin, etc.; puzzling; inexplicable: a mysterious inscription on the ancient tomb. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: mysterious (Thesaurus) mystagogue mystery Related Content Daily Word Quiz: censure Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language