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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There are some mysteries we’ll only get answered after death.—
Literary Hub,
Literary Hub,
15 Oct. 2025 -
All of these mysteries make TOI-4507 b ripe for follow-up studies.—
Paul Sutter,
Space.com,
14 Oct. 2025
Noun
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Beyond rewriting some rules of physics, the team believes this tiny engine could help tackle one of biology’s biggest puzzles—how proteins fold.—
Alice Gibbs,
MSNBC Newsweek,
10 Oct. 2025
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In other words, this explanation is plausible, but limited in its explanatory power, while simultaneously possessing the drawback of bringing up new puzzles.—
Big Think,
Big Think,
9 Oct. 2025
Noun
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The case raises urgent questions about accountability, national security, and the influence of unelected business figures inside the federal system—and whether Americans have a right to know what secrets they’re being trusted with.—
Robert Alexander,
MSNBC Newsweek,
13 Oct. 2025
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The series follows a Louvre art restorer who uncovers a cursed Mesopotamian mask tied to the storm god Baal Phegor, drawing her into a web of disappearances and dark secrets.—
Ben Croll,
Variety,
13 Oct. 2025
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“Closed books.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/closed%20books. Accessed 17 Oct. 2025.
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