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

An adaptation of Shirley Jackson’s pioneering 1959 gothic horror novel, the two-timeline series follows a group of siblings who return to their haunted childhood home after their sister Nell (Victoria Pedretti) dies there under mysterious circumstances. —David Faris, TheWeek, 23 Jan. 2026

Rather than depicting trance as exotic or mysterious, Bhanuteja wanted to explore it as an everyday communal experience. —Naman Ramachandran, Variety, 23 Jan. 2026

Both have dim, mysterious companions with unusual characteristics. —Joe Rao, Space.com, 23 Jan. 2026

Cox plays a mysterious drifter called Strindler who scours the West for the names of dead Mexican laborers and pays top dollar for them. —Georg Szalai, HollywoodReporter, 23 Jan. 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
• 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