The surname Sagorsky means literally "of the city/town Sagorsk". Sagorsk is a city near the Russian capital of Moscow. The ending of "sky" means "of" in old Russian (pre-revolution), and it is added to a surname if the family used to live in a city associated to the family. If you would add the "sky" the surname becomes Sagorsksky but because the "sk" is already in the city's name it becomes Sagorsky. This process was a common process in created surnames in Russia. The "Sagor" part of the surname sounds to me like "za gor" which is "za gorod". "Za gorod" means "a suburb of a city", in Russian. So if you take all of this into account, the surname "Sagorsky" means "of a city/town that is a suburb."