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Synonyms

mysterious

American  
[mi-steer-ee-uhs] / mɪˈstɪər i əs /

adjective

  1. full of, characterized by, or involving mystery.

    a mysterious occurrence.

    Synonyms:
    cryptic, occult, esoteric, secret
  2. implying or suggesting a mystery.

    a mysterious smile.

  3. of obscure nature, meaning, origin, etc.; puzzling; inexplicable.

    a mysterious inscription on the ancient tomb.

    Synonyms:
    impenetrable, enigmatic, incomprehensible, unintelligible, unfathomable

mysterious British  
/ mɪˈstɪərɪəs /

adjective

  1. characterized by or indicative of mystery

  2. puzzling, curious, or enigmatic

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Related Words

Mysterious, inscrutable, mystical, obscure refer to that which is not easily comprehended or explained. That which is mysterious, by being unknown or puzzling, excites curiosity, amazement, or awe: a mysterious disease. Inscrutable applies to that which is impenetrable, so enigmatic that one cannot interpret its significance: an inscrutable smile. That which is mystical has a secret significance, such as that attaching to certain rites or signs: mystical symbols. That which is obscure is discovered or comprehended dimly or with difficulty: obscure motives.

Other Word Forms

  • mysteriously adverb
  • mysteriousness noun
  • quasi-mysterious adjective
  • quasi-mysteriously adverb
  • unmysterious adjective
  • unmysteriously adverb
  • unmysteriousness noun

Etymology

Origin of mysterious

First recorded in 1610–20; mystery 1 + -ous

Explanation

Something that is mysterious has a secret-like quality that makes it hard to understand or define, like your mysterious answers that made your friends curious about what you were really up to. A dark shadow skims across the surface of lake...a strange disease makes a city's inhabitants violently ill...a large, hairy creature is spotted wandering in the woods. These situations are all mysterious because we don't know their causes. You can see the word mystery in mysterious. A mystery is a hidden or secret thing, so something that is mysterious takes effort to understand, unless it is beyond our comprehension.

Keep Reading on Vocabulary.com

Vocabulary lists containing mysterious

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

He was the first to have shape-shifting powers, which he gained after encountering a mysterious radioactive pool of protoplasm.

From Los Angeles Times • Apr. 22, 2026

Less a recondite modernist experiment than a grandly mysterious yet accessible achievement, the composition marked a profound shift in 20th-century classical music.

From The Wall Street Journal • Apr. 22, 2026

The story follows a struggling writer who is hired to complete the remaining books by an author who suffered a mysterious accident, and whose secret unfinished manuscript could reveal crucial clues.

From BBC • Apr. 17, 2026

At first glance, sea sponges seem almost too simple to be mysterious.

From Science Daily • Apr. 15, 2026

Nuthatches, warblers, sparrows, and the occasional wood dove—perfectly acceptable birds all, to be sure, but where were the sage and mysterious owls?

From "The Unseen Guest" by Maryrose Wood