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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Buoyed by this success, Congress established a series of primate research centers in the nineteen-sixties, hoping that our closest living relatives might help solve other medical mysteries, from Alzheimer’s to Zika.—
Ava Kofman,
New Yorker,
3 Nov. 2025 -
Melissa's mysteries capture interest Hurricane scientists watched with a familiar feeling of dread as Melissa traversed the Caribbean.—
Dinah Voyles Pulver,
USA Today,
2 Nov. 2025
Noun
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Then imagine there are a couple of hundred other people with very similar puzzles, also looking for particular pieces to fit their own jigsaw.—
Idaho Statesman,
Idaho Statesman,
7 Nov. 2025
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Check out the all new PLAY hub with puzzles, games and more!—
Kaycee Sloan,
Cincinnati Enquirer,
7 Nov. 2025
Noun
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Over his 95 years, Buffett has earned a reputation not only as a legendary investor, but as someone with the secrets to living a better life.—
Ryan Ermey,
CNBC,
10 Nov. 2025
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While the Frasers keep a united front against outside intruders, family secrets finally coming to light threaten to tear them apart from the inside.—
Rick Porter,
HollywoodReporter,
10 Nov. 2025
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“Closed books.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/closed%20books. Accessed 12 Nov. 2025.
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