as in to freeze
to become physically firm or solid
wait for the modeling clay to firm up before handling the finished pot
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Example Sentences
Recent Examples of Synonyms for firm (up)
Verb
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By night, the Torne River freezes into silence and the northern lights unfurl in ribbons of green and violet.—
Lewis Nunn,
Forbes.com,
24 Aug. 2025 -
Shortly after Air France Flight 447 left Rio De Janeiro for Paris, the plane’s airspeed sensors froze over—a relatively routine, transitory instrument loss due to high-altitude icing.—
David Autor,
The Atlantic,
24 Aug. 2025
Verb
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Kim and his influential sister, Korean Workers' Party Publicity and Information Department Deputy Director Kim Yo Jong, have only hardened their rhetoric against South Korea in recent years, and the North Korean ruler has simultaneously doubled down on nuclear development.—
Tom O'Connor,
MSNBC Newsweek,
23 Aug. 2025
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Russia will continue to adapt and harden its facilities, pushing Ukraine to enhance its own long-range strike systems.—
Vikram Mittal,
Forbes.com,
21 Aug. 2025
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“Firm (up).” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/firm%20%28up%29. Accessed 31 Aug. 2025.
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