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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But to defeat such a powerful villain, Prince Adam will first need to uncover the mysteries of his past and become He-Man, the most powerful man in the Universe.—
Glenn Garner,
Deadline,
6 Feb. 2026 -
There are many mysteries surrounding Big Ma’s Kitchen, which opened last spring in the former Jade BBQ and Seafood space on Garvey Avenue.—
Jenn Harris,
Los Angeles Times,
4 Feb. 2026
Noun
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Check out the all new PLAY hub with puzzles, games and more!—
Anthony Robledo,
USA Today,
12 Feb. 2026
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When shown how to open the puzzles, children copied all the steps, even unnecessary ones.—
Literary Hub,
Literary Hub,
29 Jan. 2026
Noun
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When Alice Monroe's boyfriend goes missing during their vacation in France, she's forced to uncover secrets hidden in his past.—
Marina Johnson,
Louisville Courier Journal,
8 Feb. 2026
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Paulina Porizkova is exposing some dark secrets of the high-fashion world, claiming that her rise to superstardom was paved with uncomfortable encounters.—
Stephanie Giang-Paunon,
FOXNews.com,
7 Feb. 2026
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“Closed books.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/closed%20books. Accessed 14 Feb. 2026.
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