Some characteristic forenames: Spanish Manuel, Jose, Carlos, Francisco, Jorge, Luis, Domingos, Mario, Pedro, Ana, Armando, Eduardo. Portuguese Joao, Paulo, Joaquim, Manoel, Henrique, Margarida, Albano, Batista, Guilherme, Ligia, Mateus, Sebastiao.

Portuguese and Spanish: patronymic from the medieval personal name Didacus (genitive Didaci). Compare Diego . This surname is also common in the former Portuguese colony of Goa and elsewhere on the west coast of India, having been taken there by Portuguese settlers.

Welsh: variant of Dayus, from the personal name Deiws, a pet form of Dai or Dafydd, Welsh forms of David (see Day ). In English counties bordering Wales Dayus and Dyos were sometimes shortened to Day(e)s and Deyes or altered to Dayhouse and Dyhouse, through false association with the words deyhouse, dayhouse ‘dairy’ or deyehouse, dyehouse ‘dye-works’, but there is no medieval evidence that this name derived from either word.