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 …

—Robert Houston

mysteriousness noun

Synonyms of mysterious

• cryptic
• enigmatic
• mystic
• uncanny
• obscure
• dark
• deep

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

That’s what makes Goodman’s season so mysterious, and potentially so significant as the deadline approaches. — Sam Blum, New York Times, 22 July 2026

Recently granted permission to test the mysterious statue, held in Abruzzo’s National Archaeology Museum in Chieti, central Italy, may have the answers, reports the Times of London. — Devorah Lauter, ARTnews.com, 21 July 2026

Stiller steps into the role of divorced writing professor Gus Adler, who begins to fall for a mysterious woman named Stella West (Chastain). — Hannah Malach, InStyle, 21 July 2026

Robb is set to play Smith’s young partner in the film as the two detectives enter the depths of a supermax prison to solve a mysterious murder. — Justin Kroll, Deadline, 21 July 2026

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
• deleterious
• nereus
• serious
• sirius

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