wrote the book on
phrase
informal
—used to say that someone is an expert on a particular subject
She wrote the book on long-distance swimming.
Cite this Entry
“Wrote the book on.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/wrote%20the%20book%20on. Accessed 13 Mar. 2026.
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