Surname Сиру (Cyro 
, Сиру 
) , in the world, is a very rare last name. The family name Сиру is characteristic of Brazil, where it is a very rare surname, Spain, where it is an extremely rare surname, and Venezuela. Measured by absolute frequency, it is commonest in Brazil, Nigeria, and Spain. Much more prevalently, Сиру is the forename as well as the last name.