mysterious

adjective

mys·​te·​ri·​ous mi-ˈstir-ē-əs 

1

a

: of, relating to, or constituting mystery

the mysterious ways of God

b

: 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

2

: 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

Synonyms

• arcane
• cryptic
• deep
• enigmatic
• enigmatical
• impenetrable
• inscrutable
• mystic
• occult
• uncanny

Examples of mysterious in a Sentence

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.

Recent Examples on the Web

Beyond mysterious Gathering new data about Venus is vital, Garvin pointed out, so that the next wave of exploration is grounded in what must be done first as scientists attempt to further reveal our sister world. —Leonard David, Space.com, 8 Feb. 2025

That gusher of findings will include new observations of exoplanets—or planets orbiting other stars; new surveys of the structure of the Milky Way; and new studies of dark energy, the mysterious, invisible force that causes the universe to expand continuously at an ever-accelerating rate. —Jeffrey Kluger/greenbelt, TIME, 8 Feb. 2025

With Venus swimming alongside dreamy Neptune in Pisces until Feb. 4, love could feel intuitive, mysterious and otherworldly. —Valerie Mesa, People.com, 7 Feb. 2025

Her ethereal beauty and mysterious aura captivate everyone in her orbit, but none more so than the two great loves of her youth: childhood friend Sandrino (Dario Aita) and older brother Raimondo (Daniele Rienzo). —Mike Miller, EW.com, 7 Feb. 2025

Word History

Etymology

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

First Known Use

1578, in the meaning defined at sense 1a

Phrases Containing mysterious

• be mysterious

Kids Definition

mysterious

adjective

mys·​te·​ri·​ous mis-ˈtir-ē-əs 

: containing, suggesting, or presenting a mystery

mysterious noises

also : difficult or impossible to understand

the mysterious ways of nature

mysteriously adverb