Focal segmental glomerulosclerosis (FSGS) is a mouthful of a medical term that refers to a condition that causes scarring in the kidney's filtering units. This condition can lead to kidney failure if left untreated. While FSGS is the most commonly used term to describe this condition, there are other synonyms that can be used interchangeably. These include: focal glomerular sclerosis, focal sclerosis, segmental sclerosis, and glomerulosclerosis. It's important to note that regardless of the terminology used, FSGS requires close monitoring and medical treatment to manage its progression and prevent irreversible damage to the kidneys.