PSEUDONYM (Gr. ψευδώνυμος, having a false name, ψευδής, false and ὄνυμα, name), a false or invented name, particularly the fictitious name under which an author produces his work in order to conceal his identity. The same end is gained by publication without any name, i.e. anonymously (Gr. ἁνώνυμος, without a name). The body of works thus produced either without the author's name or under a fictitious name is known as anonymous and pseudonymous literature, and many books have been published affording a key to the identity of the various writers, forming an important section of bibliography. Though Fredericus Geisler published a short treatise on the subject entitled Larva detracta, &c., in 1669, the chief early work was that of Vincent Placcius (1642–1699) whose Theatrurn anonymorurn et pseudonymorurn was published in 1708, edited by L. F. Vischer with a preface and life by J. A. Fabricius; supplements were published in 1711 and in 1740. The next important work, only a fragment of the purposed scheme, was that of Adrien Baillet (q.v.), under the title of Auteurs déguisés sous les noms étrangers, &c. (1690). Antoine Alexandre Barbier (q.v.) published his standard work Dictionnaire des outrages anonymies et pseudonymes in 1806–1809 (2nd ed., 1822–1827). This was followed by the Supercheries littéraires dévoitées of J. M. Quérard (q.v.). The third edition of Barbier's work, embodying Quérard and much new matter, was published in 1872–1879. This was edited by P. Gustave Brunet, who published a supplement in 1889. Other works in French are those of C. Jolliet, Les Pseudonymes du jour (1867 and 1884), and F. Drujon, Livres à clef (1888). Of German works in this sphere of bibliography the Index pseudonymorurn, Wörterbuch der Pseudonymen of Emil Weller appeared in 1856, of which several supplements were published later. The most monumental of all works are the Deutsches Anonymen-Lexikon, 1501–1850, by M. Holzmann and H. Bohatta (1902–1907), supplement, 1851–1908 (1909), and the Deutsches Pseudonymen-Lexikon, by the same authors (1906). See also F. Sintenis, Die Pseudonyme der neueren deutschen Literatur (1899), and the supplementary volume (1909), to Meyers's Konversations-Lexikon (6th ed.). The chief Italian work is the Dizionario di opere anonime e pseudonime di scrittori italiani, by G. Melzi (1848–1859), with supplement by G. Passano (1887). The Dutch Vermomde en naamlooze schrijvers . . . der Nederl. en Vlaarnschen letteren, by J. I. van Doorninck (1883–1885), was a second edition of an earlier work. The Academy of Upsala is publishing, under the editorship of L. Bygden, a Swedish dictionary Svenskt anonym och pseudonym lexikon (1898), &c. England was late in entering the field. The first work actually published was the Handbook of Fictitious Names, by R. Thomas (Olphar Hamst) (1868). Samuel Halkett, and the successor to his compilations, John Laing, both died before their work was published; edited and revised by Miss C. Laing it appeared in 1882–1888 in 4 vols. as the Dictionary of the Anonymous and Pseudonymous Literature of Great Britain, by S. Halkett and J. Laing. This remains the standard work on the subject in English. Other works are W. Cushing, Initials and Pseudonyms (American and English from the beginning of the 18th century); 2nd series (1886, 1888), and Anonyms (1890); F. Marchmont, A Concise Handbook of Literature issued under Pseudonyms or Initials (1896); see also especially W. P. Courtney, The Secrets of our National Literature (1908), the first chapter of which contains a sketch of the history of the subject, to which the above account is mainly due. The anonymous and pseudonymous Latin literature of the middle ages has been treated in modern times by A. Franklin, Dictionnaire des noms, &c., latins 1100–1530 (1875), and A. G. Little, Initia operum latinorum saec. 13–15 (1904).