Cognomen سيدنى (Sydney 
, سيدنى) , all over the world, is a common last name. The last name سيدنى is characteristic of Saint Lucia, where it is quite a common surname, Trinidad and Tobago, and Mauritius, where it is quite a rare surname. Not in comparison with a country's population, this name is the most popular in Nigeria, Australia, and the United States. More prevalently, سيدنى is the forename as well as the last name.