as in mysteries
something hard to understand or explain
the couple's unorthodox marriage is definitely a closed book to those outside of the relationship
Synonyms & Similar Words
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Example Sentences
Recent Examples of Synonyms for closed books
Noun
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Because George, portrayed by Hugh Jackman, routinely read mysteries to his charges before his sudden demise, these sheep aren’t complete novices, said Wilson Chapman in IndieWire.—
The Week US,
TheWeek,
18 May 2026 -
The axolotl is one of evolution’s greatest biological mysteries.—
Scott Travers,
Forbes.com,
16 May 2026
Noun
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Thank you again from all the Daily News readers who do her puzzles.—
Voice of the People,
New York Daily News,
14 May 2026
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Check out the all new PLAY hub with puzzles, games and more!—
Amaris Encinas,
USA Today,
14 May 2026
Noun
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Lebedev also mentioned that the dozens of production secrets and a number of patented solutions were used in the manufacture of reactor units.—
Abhishek Bhardwaj,
Interesting Engineering,
15 May 2026
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Both teenagers are hiding secrets; Johnny, a potentially career-ending injury, and Shannon, a troubled and violent home life.—
Arushi Jacob,
Variety,
15 May 2026
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“Closed books.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/closed%20books. Accessed 21 May. 2026.
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