This is a very interesting Portugese surname of some antiquity. According to a recent Dictionary of Surnames, it derives from the Roman (Latin) word 'collact' meaning 'with milk', and originally referred to an infant child, one who for whatever reason had to be wet nursed. However it seems that the precise meaning is more general, as wet nursing was widely practiced by the nobility, and the name was sometimes given as a form of nickname for a foster child or even a stepchlld. The Romans occupied the Iberian Peninsula of Spain and Portugal for some four hundred years from the 1st to the 5th century a.d. They left behind many examples of their culture of which the language, whether Spanish or Portugese, is a vivid reminder. This surname is quite well recorded in surviving early church registers, and according to the International Genealogical Index, particulary at Ilha da Graciosa. Examples of recordings include Antonio Martins Colaco who married Catarina Correia at Ilha da Graciosa, Angra Do Herosimo, in 1704, and Manuel de Sousa Colaco, who married Maria de Sousa da Silva, at the same place, on July 14th 1829.