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

During the course of the series, Mullen's investigation into the cyberattack unearths the mysterious weapon. —Gordon G. Chang, Newsweek, 4 Mar. 2025

There are dramatic headlines, nonsensical abbreviations and mysterious trends that seem to erase people’s money. —Catherine Brock, Forbes, 4 Mar. 2025

The Scholars, out May 2 on Matador Records, features at least a dozen distinct characters, in settings that include a mysterious university and a clown school. —Simon Vozick-Levinson, Rolling Stone, 4 Mar. 2025

Researchers in northern Denmark have unearthed evidence of a mysterious circle of wooden posts dating back 4,000 years. —Sonja Anderson, Smithsonian Magazine, 4 Mar. 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

Rhymes for mysterious

• delirious
• imperious
• cereus
• nereus
• serious
• sirius
• deleterious

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