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put one's thinking cap on

idiom

informal
: to start trying to think of what should be done

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put one's shirt on
put one's thinking cap on
put one foot in front of the other
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“Put one's thinking cap on.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/put%20one%27s%20thinking%20cap%20on. Accessed 29 Nov. 2025.

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