DOUGHBOY, in the 17th century, signified "dumpling," During the American Civil War it was applied to the mass buttons on uniforms and thence to infantrymen. At a period not exactly ascertained the word was supposed to come from the dough-like appearance of a uniform soiled by moistened pipe-clay. Again, infantrymen were said to march in "dough" during wet weather. "Adobe" furnishes a similar derivation, although it may be a "popular etymology," or wholesale transference of a foreign word to an English meaning and spelling. "Doughboys" was a favourite designation for the United States soldiers during the World War.
See J. H. Moss, Officers' Manual (1909) ; G. P. Krapp, The English Language in America (2 vols., 1925).