mys·​te·​ri·​ous mi-ˈstir-ē-əs How to pronounce mysterious (audio)
: of, relating to, or constituting mystery
the mysterious ways of God
: exciting wonder, curiosity, or surprise while baffling efforts to comprehend or identify : mystifying
heard a mysterious noise
a mysterious stranger
a mysterious plane crash
a mysterious illness
: stirred by or attracted to the inexplicable
… to help a mysterious wizard … ward off the end of the world with blood sacrifices.Robert Houston
mysteriousness noun

Example Sentences

the mysterious ways of nature We heard a mysterious noise outside our tent. He died under mysterious circumstances. A mysterious illness has been spreading through the city. There's something mysterious about that old woman. Her behavior was very mysterious. See More
Recent Examples on the Web Geoscientists have made an unprecedented achievement on their 60-year quest to know more about Earth's mysterious depths. Camille Fine, USA TODAY, 6 June 2023 After spending the episode going undercover in a prison to discover the culprit behind a mysterious Russian attack, the agent learned from Evelyn Shaw (guest star Juliette Goglia) that inmates knew a federal agent was among them. Adrianna Freedman, Good Housekeeping, 6 June 2023 Set to clean up Earth after humans turned it into a wasteland, lonely Wall-E finds love with the mysterious Eve and ends up in space, trying to save the human race. Angel Madison, Country Living, 6 June 2023 The high bidder was a mysterious collector who phoned in, and an auction representative raised the paddle in their place. Emily St. Martin, Los Angeles Times, 6 June 2023 Take a stroll through the Sallie House, the former home of a local physician where visitors have experienced mysterious chills and the random movement of objects (overnight stays are welcome). Laura Kiniry, Smithsonian Magazine, 6 June 2023 Cal and Olive, who were forced to grow up quicker than anyone else implicated in this mysterious flight, are revealed to be younger with no recollection of what has happened in the last 11 years, much like everyone else who wasn’t on the flight. Max Gao, ELLE, 5 June 2023 New walking tour explores the mysterious case A few people, like Col. Cameron French, had political ties. Maggie Menderski, The Courier-Journal, 5 June 2023 The vast majority of these interpreters have been men who projected onto the mysterious sorceress their own fears and fantasies of the feminine. Jeremy Eichler,, 5 June 2023 See More

These examples are programmatically compiled from various online sources to illustrate current usage of the word 'mysterious.' Any opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.

Word History


mystery entry 1 + -ous, probably after Middle French mysterieux

First Known Use

1578, in the meaning defined at sense 1a

Time Traveler
The first known use of mysterious was in 1578

Dictionary Entries Near mysterious

Cite this Entry

“Mysterious.” Dictionary, Merriam-Webster, Accessed 8 Jun. 2023.

Kids Definition


mys·​te·​ri·​ous mis-ˈtir-ē-əs How to pronounce mysterious (audio)
: containing, suggesting, or presenting a mystery
mysterious noises
also : difficult or impossible to understand
the mysterious ways of nature
mysteriously adverb

More from Merriam-Webster on mysterious

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