Monoclonal gammopathy of undetermined significance (MGUS) is a term used to describe a condition in which there is an abnormal protein known as a monoclonal protein (M protein) present in the blood. There are no specific synonyms for MGUS, but some commonly used terms to describe it include: asymptomatic M protein, benign monoclonal gammopathy, monoclonal protein in blood, and unexplained protein in blood. While MGUS is not a cancerous condition, it may increase the risk of developing certain types of blood cancer, such as multiple myeloma. Therefore, regular monitoring by a healthcare professional is necessary to ensure early detection and treatment if necessary.