coauthor

American  

[koh-aw-ther, koh-aw-] / koʊˈɔ θər, ˈkoʊˌɔ- /

noun

1. one of two or more joint authors.

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verb (used with object)

1. to write in joint authorship.

coauthor British  

/ kəʊˈɔːθə /

noun

1. a person who shares the writing of a book, article, etc, with another

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verb

1. (tr) to be the joint author of (a book, article, etc)

Etymology

Origin of coauthor

First recorded in 1860–65; co- + author

Explanation

A coauthor is someone who works with another person to write something. If three people take turns writing chapters of a novel, each of them can call herself a coauthor. You can spell the noun coauthor with or without a hyphen — co-author is also correct. Whenever it takes more than one person to write a book, the book can be said to have coauthors. And if you collaborate with a friend on a hand-written magazine, you are one of its coauthors. The word comes from author, or writer, and the prefix co, which means "together" or "mutually."

Example Sentences

"A four-decade growth phase may have allowed younger tyrannosaurs to fill a variety of ecological roles within their environments," says coauthor Jack Horner of Chapman University.

From Science Daily • Mar. 5, 2026

Fernando and his coauthor, Constantinos Charalambous, a research fellow at Imperial College London, tested the technique by analyzing the reentry of debris from China's Shenzhou-15 spacecraft.

From Science Daily • Jan. 24, 2026

One of those senators, Russ Feingold—the coauthor of the McCain-Feingold campaign finance law—was particularly vulnerable, as he was up for reelection that year.

From Slate • Oct. 21, 2025

I have already written one cookbook as a coauthor called Mexican Food: The Ultimate Cookbook by Cidermillpress.

From Salon • Jan. 4, 2025

D’Alembert is best known for his collaboration on the famed Encyclopédie of human knowledge—a 20-year effort with coauthor Denis Diderot.

From "Zero: The Biography of a Dangerous Idea" by Charles Seife