Master etymologist Gerald Cohen knows how jazz got its name, why they’re called hot dogs, and much moreOut in the wilds of western Missouri, in Rolla, which is not far from the tornado-devastated town of Joplin, lives a scholar who has made etymology his life’s work. He is Gerald Leonard Cohen, professor in the department of arts, languages, and philosophy at the Missouri University of Science and Technology, and grand impresario of American etymologists—as well as the world’s leading corraler of language historians, who often join him in tackling some of the most challenging puzzles of word origins. Cohen does...