also chapbook, 1812, from chap, short for chapman, so called because chapmen once sold such books.
One of a class of tracts upon homely and miscellaneous subjects which at one time formed the chief popular literature of Great Britain and the American colonies. They consisted of lives of heroes, martyrs, and wonderful personages, stories of roguery and broad humor, of giants, ghosts, witches, and dreams, histories in verse, songs and ballads, theological tracts, etc. They emanated principally from the provincial press, and were hawked about the country by chapmen or peddlers. [Century Dictionary]