Etymology
''Tiago'' hypothesis
Diego has long been interpreted as variant of ''Tiago'' (Brazilian Portuguese: ''Thiago''), an abbreviation of ''Santiago'', from the older ''Sant Yago'' "Saint Jacob (name), Jacob", in English known as James the Great, Saint James or as ''San-Tiago''. This has been the standard interpretation of the name since at least the 19th century, as it was reported by Robert Southey in 1808 and by Apolinar Rato y Hevia (1891). The suggestion that this identification may be a folk etymology, i.e. that ''Diego'' (and ''Didacus''; see below) may be of another origin and only later identified with ''Jacobo'', is made by Buchholtz (1894), though this possibility is judged as improbable by the author himself.''Didacus'' hypothesis
In the later 20th century, the traditional identification of ''Diego'' = ''Jacobo'' came to be seen as untenable. Malkiel (1975) calls the equation an "odd couple" (''extraña pareja''). The name ''Didacus'', while unattested in antiquity, predates the earliest record of the form ''Diego''. The oldest record for ''Didacus'' according to Floriano (1949) dates to 747, with numerous further records during the 9th century. Becker (2009) argues against possible derivation from the Greek language, Greek name ''Diadochus (disambiguation), Diadochus'', but also against suggestions of Basque language, Basque and Celtic languages, Celtic derivations.Lidia Becker, ''Hispano-romanisches Namenbuch: Untersuchung der Personennamen vorrömischer, griechischer und lateinisch-romanischer Etymologie auf der Iberischen Halbinsel im Mittelalter (6.–12. Jahrhundert)'' (De Gruyter, 2009), pp. 385–392. ''Didacus'' is recorded in the forms ''Diaco'' and ''Diago'' in the 10th century. The form ''Diego'' is first recorded in the late 11th century. Its original derivation from ''Didacus'' is uncertain, among other things because the shift from ''-ía-'' to ''-ié-'' is unexplained (Becker 2009:386). The name ''Diego Gonzalez'' is given to a character in the ''Cantar de mio Cid'', a 12th-century poem. It has been argued on metrical grounds that the name ''Diego'' in the ''Cantar'' represents an original ''Díago''.Becker (2009:386). Medieval bearers of the name, such as Diego de Acebo (d. 1207), are recorded as ''Didacus'' in contemporary sources. ''Diego'' becomes the standard form of the name in the 14th century, and it is frequently given in the 16th century, e.g. Diego Laynez, 1512–1565. The city of San Diego was named for the flagship of Sebastián Vizcaíno (1602), which was itself named for Didacus of Alcalá (d. 1463).As a patronym
The patronym for Diego is ''Díaz (surname), Díaz'' in Castilian Spanish (used for example by Rodrigo Díaz de Vivar, better known as El Cid) and ''Dias (surname), Dias'' in Portuguese. Like many patronymics, these have become common surnames among Iberophones worldwide. The form ''Diéguez'' is much less common; ''Diegues'' can be found in Lusophone countries. Diego (surname), ''Diego'' and ''de Diego'' can also be found as surnames.As an ethnic term
"Diego" as a metonym for a Spaniard is documented from around 1615. The term "Dago (slur), Dago" as a generic name for Spaniards is recorded in the 19th century and may possibly be a derivation from ''Diego''. By the early 20th century, the term ''dago'' or ''dego'' was extended as an ethnic slur applied chiefly to Italian Americans, besides also for anyone of Spanish people, Spanish or Portuguese people, Portuguese descent.See also
* List of people with given name Diego * Saint Diego (disambiguation)References
{{Reflist Spanish masculine given names ca:Dídac nl:Diego pt:Diego